Heat oil in 3-quart saucepan or Dutch oven over medium-high heat. Add bell pepper, onion and garlic and cook and stir 5 minutes or until tender. Add tomatoes, beans, corn, water, rice, chili powder and cumin; stir well. Bring to a boil. Reduce heat; cover. Simmer 30 minutes, stirring occasionally. To serve, top with sour cream, if desired.