Puree in blender:

3 cups cooked black, red, pinto, or Anasazi beans with liquid (750 ml)
2/3 onion, chopped (75 ml)
1-2 cloves garlic, crushed
1/4 cup green pepper, chopped (50 ml) (optional)
1 Tbsp cumin

Simmer bean purée uncovered with 3 more cups of whole beans and salt to taste until beans thicken, 10-15 minutes. Form into loaf on serving plate.