Drain and rinse 100g black beans and crush with a fork in a bowl. Stir in 100g of lean minced beef and a small, beaten egg. Season with ground black pepper and a dash of Worcestershire Sauce. Wash your hands and then shape into two burgers. Heat a non-stick frying and brush with olive oil. Cook the burgers for 5 minutes, then turn and cook the other side. Slice a wholemeal roll in half and lightly toast. Spread one side with ketchup and one with low fat mayonnaise. Put the burgers on the buns, followed by lettuce, slices of tomato and onion /pickled gerkin (optional) and serve. Follow with 175g bowl each of fresh fruit salad.