Black Beans; Southwestern

• 2 celery stalks (chopped)
• 1 onion (chopped)
• 1 green pepper (chopped)
• 1 tomato (chopped)
• 1 bay leaf
• 1 orange unpeeled
• 700 ml water
• 260 gr black beans (dried)
• 10 ml vegetable oil
• 5 ml vinegar (white)