Place the lamb steaks between 2 sheets of clingfilm on a board and bash with a rolling pin until half thickness. Remove the clingfilm and season each side with a little pepper, then sprinkle each side with the curry powder to lightly coat.
Heat the oil in a large frying pan and cook the steaks over a high heat for 3–4 minutes on each side until cooked through.
Place the bread slices on a board and top each of 2 slices with 1 tablespoon mango chutney, then top with the hot lamb steak. Scatter with the salad leaves, and top each with another slice of bread.
Cut each sandwich in half diagonally and serve 1 half per child.