Heat olive oil in a large stock pot. Sauté onions until softened. Add garlic and cook until fragrant. Add ground beef and sausage, using a wooden spoon to break apart and brown the meat. Add chili powder, paprika, cumin, oregano, and red pepper flakes. Cook spices until fragrant, about 1 minute. Add bell peppers, eggplant, zucchini, tomatoes and their juices, kidney and black beans, and corn. Simmer on very low heat for 20–30 minutes. Serve over rice.