1. Turn a 5 quart slow cooker on high (for a smaller slow cooker, use about half this recipe). Add the diced white onion(1/2) and garlic(2 cloves), drained canned kidney beans(30 oz), drained canned black beans(15 oz), drained canned pinto beans(15 oz), diced tomato(15 oz), green bell pepper(2) and corn kernels(1.5 cups). Pour in vegetable stock(2.5 cups), medium red salsa(1 cup), cumin(2 tsp) and cayenne pepper(1 tsp). Stir gently to combine.
2. Cook in the slow cooker for 3-4 hours on high, 7 on low (depending on your stock pot).
3. Add salt to taste. Ladle into bowls and top with green onion, cheddar cheese and a dollop of sour cream (skip sour cream and cheddar cheese for vegan version).