Perhaps your new favorite bean dish:
Blend the tomatoes with half the onion, garlic, oregano and salt to taste in a hand blender. Thicken the puree in hot oil while stirring. Also blend the beans with the cooking liquid. Add to the tomato mixture form and gently simmer for 5-10 minutes until the flavors are completely blended. Garnish the soup with oregano, cheese and tortilla wedges and bring to the table.