Gemara

(Beraisa): If one was Motzi [on Shabbos from Reshus ha'Yachid to Reshus ha'Rabim] a Shi'ur of food in a Kli, he is liable for the food and exempt for the Kli;

If he needed the Kli (for something else), he is liable even for the Kli.

Berachos 36b (Rav and Shmuel): One blesses Borei Minei Mezonos on anything containing [any of] the five species of grain.

39a (Rav Ashi citing Rav Kahana): Little flour is added to a cooked beet dish, so we bless on it Borei Pri ha'Adamah. Much flour is added to a cooked turnip dish, so the blessing is Borei Minei Mezonos.

Retraction (Rav Kahana): We bless Borei Peri ha'Adamah on both of them. Much flour is added merely to make it stick together.

Rishonim

Rambam (Hilchos Berachos 3:6): Anything mixed in to make a food stick or to give scent or color is Tefel. If it (the flour) is added to give taste, it is Ikar. Therefore, honey that is cooked and they put in choice wheat in order to make it stick together, and make sweets from it, we do not bless on it Borei Minei Mezonos, because the honey is Ikar.

Rosh (Berachos 6:7): If flour is put in a Tavshil to congeal it or make it stick together, this is not considered Ikar, like we say about a beet dish.

Tosfos (36b DH Kol): When they put flour into beans or lentils, or into almonds for a Choleh, if it is for sustenance, the one blesses Borei Minei Mezonos. If it is merely in order to make it stick together, one need not bless Borei Minei Mezonos. It is good to eat it only within a meal after ha'Motzi, and it is exempt in any case.

Shitah Mekubetzes (39a DH v'Lo): Even though there is much flour, it is merely to make it stick. I.e. it is not Ikar in the Tavshil. It is Ikar when the flour is added in order to eat it. Even if there is a little flour, one blesses Borei Minei Mezonos, for we hold like Rav and Shmuel. However, this is only if there is k'Zayis bi'Chdei Achilas Pras. If not, it is not important at all.

Poskim

Shulchan Aruch (OC 208:3): When they put flour into almonds for a Choleh, if it is for sustenance, the one blesses Borei Minei Mezonos. If it is merely in order to make it stick together, one does not bless Borei Minei Mezonos. It is good to eat it only within a meal after ha'Motzi, and it is exempt Mimenah (from it).

Taz (4): It seems that even if the five grains are the majority, since they are not l'Ma'achal (for the sake of eating it), they do not have the importance of food to bless on them Borei Minei Mezonos. Even though regarding other things we follow the majority, here is different, for they are not considered food, since they are merely to make it stick. However, one should not be so lenient when grain is the majority, since he gets significant benefit from it. We find like this in YD 103:2. There, some are stringent that if the Isur increased the size of the mixture, we do not permit due to Nosen Ta'am li'Fgam (the Isur harms the taste of the Heter), for he benefits from the increased size. Also here, it is important even though it is only to make it stick. It seems that this is the Safek of Tosfos, and the Shulchan Aruch brought it. It is good to be stringent and eat it in a meal. The Shulchan Aruch did not mention this in Sa'if 2, for there the grain is not the majority.

Mishnah Berurah (11): It is good to be stringent because it is normal to put flour in for sustenance, and it is difficult to determine whether the intent was only to make it stick.

Avnei Nezer (OC 38): They often add into ground meat 10% flour or bread (crumbs). The producers say that it is in order to make it softer and easier to eat. My mother says that it is also to increase the volume. The Gemara explicitly says that if it is in order to make it stick together (we do not bless Borei Minei Mezonos). Making it easier to eat is like making it stick. The Rambam says that we bless Borei Minei Mezonos only if it is added for taste. Tosfos says that we bless Borei Minei Mezonos if it is added for sustenance. Here, to make it softer is like what the Rambam wrote that anything added to make stick or for scent or color is Tefel, so one blesses sheha'Kol.

Avnei Nezer (3): The Shitah Mekubetzes says that it depends on whether the flour was added in order to eat it. Making the meat softer is not intent for eating the grain. However, increasing the volume could be considered intent to eat it. I.e. he will eat more, including the grain. Even though he intends to soften it, he also intends for eating, so it is not Tefel. We similarly say that one who was Motzi food in a Kli is liable for the food and exempt for the Kli. If he needed the Kli, he is liable even for the Kli. Here also, since he intends both for sticking and for eating, it is not Tefel. However, I saw in Piskei Ri'az that if flour is added to thicken, he blesses sheha'Kol. Also, perhaps increasing the volume is in order to make the meat softer and inflated, but not that he intends for eating the flour.

Avnei Nezer (4): Also according to Rav Kahana's initial reasoning, that flour in the turnip and beet dishes is not to make it stick, one should bless Borei Minei Mezonos even on the beet dish, even though there is little flour, for Rav and Shmuel say so for anything with grain! It is difficult to say that Rav Kahana knew that when there is little flour, it is to make it stick. The Gemara connotes that (he thought that) they put much flour (in turnips) in order to make it stick together, and a little flour (with beets) for the sake of eating, and even so one does not bless Borei Minei Mezonos.

Avnei Nezer (5): It seems that according to Tosfos, when the flour is for sustenance, even if there is a little flour, it is not Tefel, since the other ingredients do not sustain like grain does. If so, Rav and Shmuel did not discuss when the flour is for taste. Then, it depends on the majority. If the grain is only to make it stick, even if it is the majority, he blesses the Berachah of the other species, like the Bach says, unlike the Taz. Rav Kahana initially thought that one blesses Borei Minei Mezonos on the turnip dish, because it has much, i.e. a majority of flour. He concluded that even so, since it is only to make it stick, it is Tefel.

Avnei Nezer (6): According to Tosfos, there are three laws. When the flour is for sustenance, even if there is a little, one blesses Borei Minei Mezonos. When the flour is not for sustenance, but it is for eating, it depends on the majority, like Rav Kahana thought. When he does not intend even for eating it, he blesses on the other species. The Rambam holds that if it is for taste, even if there is a little, he blesses Borei Minei Mezonos. The Shitah Mekubetzes says so whenever it is for eating. If so, initially Rav Kahana should have held that one blesses Borei Minei Mezonos even on a beet dish! We can answer based on the Shitah, who says that when there is not k'Zayis bi'Chdei Achilas Pras, one blesses on the other species.

Avnei Nezer (10): Even if it is a Safek whether the flour in patties is only to make it stick, if one blessed sheha'Kol he was Yotzei.

Note: Likewise, if one blessed Borei Minei Mezonos on anything except for water or salt, he was Yotzei! However, sheha'Kol is better than for it was enacted to bless on foods for which one cannot determine the Berachah.

Note: This similarly affects one who eats Shnitzel in which the flour is less than k'Zayis bi'Chdei Achilas Pras.

Pri Chodosh (YD 112:17): The Rashbatz and Rivash (28) say that honey is Ikar in sweets made of flour and honey, therefore there is no Isur of Bishul Akum (a Rabbinic decree forbidding food cooked by Nochrim), and one blesses sheha'Kol on them. I say that Bishul Akum applies, and one blesses Borei Minei Mezonos. I was asked about wine that is boiled, and they add a minority of flour to thicken it. I proved that if the flour is merely to make it stick, it is Tefel and we bless on the Ikar. However, Stam flour put into a liquid is not only to thicken it. It also is Machshir and improves it for eating. Therefore, one blesses Borei Minei Mezonos. I heard that in Chevron they bless Borei Minei Mezonos.

Be'er Heitev (3): There is a food made of eggs and sugar, and they add flour when they put it on the fire. The flour is only to make it stick, so one blesses sheha'Kol. However, the Pri Chodosh says that the flour also is Machshir, so one blesses Borei Minei Mezonos. Zera Avraham agrees.

Ohr l'Tziyon (2:14:19): If bread crumbs are put in patties or Shnitzel to make it stick together, one blesses sheha'Kol. If they are added for sustenance, or even just for taste, one blesses Borei Minei Mezonos. The same applies to bread crumbs or flour added to Falafel. The Berachah on most Falafel sold today is Borei Minei Mezonos.

Yalkut Yosef (OC 204:2, and She'eris Yosef 2): The custom is to bless sheha'Kol on patties of meat, vegetables and flour, or on meat fried in bread crumbs and eggs. Simchas Kohen (5 OC 208) says that the flour is merely to make it stick, so it is Batel. Avnei Nezer and Sha'ar Shimshon (2:145) say similarly. However, it is better to eat them in a meal. The Shulchan Aruch says so about flour put into almonds, for it is normal to do so for sustenance, and it is difficult to determine the intent. Some distinguish between Shnitzel made in the house from that made in wedding halls and hotels. In the latter places, they want to save meat, so they add much flour with intent for taste and to be Machshir. In the house, one intends merely to make it stick for frying. My father (ha'Gaon R. O Yosef Shlita) disagrees. In general, the flour is only to make it stick, and not for sustenance.

Rivevos Efrayim (3:122): R. Shmuel Forst says that ha'Gaon R. M. Feinstein Ztz"l says that one blesses Borei Minei Mezonos if the bread crumbs are for taste, and sheha'Kol if they are merely in order to fry it. However, R. Forst holds that they are always for taste, so one blesses only Borei Minei Mezonos. (However, southern fried chicken has much meat, so it is a Safek. One should bless Mezonos on the breading, and sheha'Kol on something else to exempt the chicken.) R. Mordechai Tendler said in R. Moshe's name that if one wants to eat the breading of Shnitzel, he blesses Borei Minei Mezonos on it, and sheha'Kol on the meat. R. S. Eider said that R. Moshe always blessed sheha'Kol. Ha'Gaon R. Y. Zilber Shlita says that one always blesses sheha'Kol, even if there is much breading and only a little meat, like in Yeshivos in Eretz Yisrael. He was almost sure that ha'Gaon R. Y.S. Elyashiv Ztz"l agreed. Ha'Gaon R. Y. Kaminetzsky Ztz"l says that one blesses sheha'Kol. Some say that he explained that the breading is not important, even though it is for taste.

V'Zos ha'Berachah (p.110): Ha'Gaon R. C.P. Scheinberg Ztz"l says that one should say both Berachos. Ha'Gaon R. Y.S. Elyashiv Ztz"l says that if the breading is thick, one blesses just Borei Minei Mezonos. One who wants to fulfill all opinions can separate a piece of breading, bless sheha'Kol on it (with intent to exempt the Shnitzel, if possible), and then sheha'Kol on another food. If he has no other food, he can separate a piece of the meat before blessing on the breading, and bless on the meat after blessing on the breading.