Preheat oven to 375°F (190°C). Rinse out your black beans in a strainer and spread them out onto a baking sheet. Bake them for about 5-10 minutes or until they're starting to get dried out.
While that's going on, put your skillet over medium heat with your olive oil. Sautée the onions, pepper, and garlic until they're soft. That'll take around five minutes or so.
Use your sautéing time to start cooking your kasha. First, fill a small saucepan with 3/4 cup water over high heat until boiling.
While the water is heating up, mix 1/4 cup of kasha with one egg in a small bowl with a dash of salt and black pepper. Stir with a fork until the kasha is covered.
When the water is boiling, pour in the kasha and turn down the heat to low so it simmers. Keep an eye on it, mixing the kasha occasionally, making sure it doesn't burn.
From there, you can use a food processor or put everything in a large bowl with the other ingredients. That's your matzo meal, eggs, feta cheese, horseradish (optional), BBQ sauce (optional), kasha, and spices. Mix everything together. Then, add the black beans and start mashing them. Leave some chunks of black beans un-smashed.
Form your mix into patties using about 1/3 cup of mixture for each one.
Places the patties on parchment paper and bake them at 375°F (190°C). After 10 minutes, flip them over. They can be done after 20 total minutes or you can throw them back onto the skillet for a couple of minutes each side over medium heat.