In a large pot over medium heat, heat oil. Add ground beef and cook, stirring occasionally, until lightly browned.
Remove excess oil, except about 1 tablespoon. Season meat with salt and pepper to taste.
Add onions and garlic and cook for about 1 minute or until softened.
Add bell peppers and cook for about 1 minute or until tender.
Add stewed tomatoes, kidney beans, black beans, salsa, chili powder, cumin and cayenne pepper. Stir to combine. Continue to cook about 6 to 7 minutes or until heated through.
Transfer to serving bowls. Garnish with tortilla strips, sour cream, cheese, chopped onions, and green onions, if desired. Serve hot.