Soak black beans, preferably overnight, in 1/2 litre of cold water. Put beans and soaking water, as well as broth in a pot. Bring to the boil, cover and cook for about 50 minutes. Add some salt about 5 minutes before the end of the cooking time. Drain the beans and let them cool down.
In the meantime drain wax beans. Peel and finely chop the onion. Cut the chilli lengthwise, remove seeds, wash and cut into rings. Clean, wash and drain lettuce. Cut all but 4 beautiful leaves into fine strips for serving. Mix lemon juice, a little salt, onions, chilli and Chinese sauce. Whip the oil into it. Mix the black beans, wax beans and crabs with the marinade and let it stand for a short time. Fold in the salad strips just before serving.
Cut all but 4 beautiful leaves into fine strips for serving. Mix lemon juice, a little salt, onions, chilli and Chinese sauce. Whip the oil into it. Mix the black beans, wax beans and crabs with the marinade and let it stand for a short time. Fold in the salad strips just before serving. Arrange on plates garnished with the remaining salad leaves