Heat the olive oil in a skillet over medium-high heat, and cook garlic and onion until onion is tender. Stir in the green bell pepper, and cook until tender but firm. Season with cumin, mustard, cayenne pepper, salt, and black pepper.
Stir the kidney beans with liquid and corn with liquid into the skillet. Bring to a boil, reduce heat to medium, and continue cooking 20 minutes, stirring occasionally. Serve immediately.