- In a deep wide pan, combine tomatoes, kidney beans, butter and pinto beans, water, tomato paste, undrained chilli peppers, onions, courgette, chilli powder, cumin, garlic powder, sugar, salt to taste, if desired.
- Heat to boiling; reduce heat.
- Simmer, covered, 30 minutes.
- Remove from heat.
- Add cheese; stir until melted.
Serve with sour cream and garnish with corriander, if desired.