In a saucepan, cook onion, garlic, red pepper, and chili pepper in butter over medium heat until tender.
In a large bowl, stir together the onion mixture, beans, yolks, cilantro, hot-pepper sauce, cumin, and black pepper. Add 1/2 cup of the bread crumbs to form a mixture that holds together.
Using 1/4 cup of the mixture at a time, shape into 1/2-inch-thick patties. Coat with the remaining bread crumbs.
In a skillet, cook patties in hot oil over medium-high heat for 4 minutes per side or until golden and heated through. Add additional oil, if necessary, during cooking.
Drain on paper towels. Keep warm in a 300 degree F oven while cooking remainder. Serve with dollops of sour cream and snipped chives, if you like. Makes 12 patties (6 to 8 appetizer servings).