Clean, wash and chop the beans. Cook in little boiling salted water for about 10 minutes. Then drain, rinse with cold water and let drain. Peel onion and cut into thin rings. Clean, wash and cut the bell peppers into pieces.
Wash the tomatoes. Clean, wash, spin-dry and chop the lettuce.
For the dressing mix the stock and both vinegars. Drain oil from the tuna can and collect. Beat the oil from the tin or olive oil vigorously into the dressing. Season with salt and pepper.
Mix beans, peppers, tomatoes, onion, salads and dressing. Serve tuna in the can with the Nice salad. Baguette tastes good with it.