If using bouillon cubes, drop cubes into the water to dissolve and set aside until needed.
Add oil to a large pot. Over medium heat, saute the onions until soft, before adding the garlic, carrots, peppers and chilies.
Mix in coriander, cumin, paprika and chili powder. Cook until fragrant, then toss in the tomatoes and buckwheat. Stir well.
Pour in stock or water with bouillon cubes to the pot. Season with salt and pepper to taste.
Bring to a boil, reduce to a simmer and cook for about 25 to 35 minutes. Cooking time depends on how soft you like your buckwheat. I prefer it just over al dente in this recipe because it closely matches the texture of meat at that point.
Add in the black beans, cook for a few more minutes. Do not overcook or you will have mushy beans and buckwheat. Not a great combination.
Check seasoning again and then serve hot with your choice of toppings.
Like most chilies, this one is better the next day as the flavor melds.