Peel and finely chop the garlic. Cut off the fat from the rump steaks and cut the steaks crosswise into thin slices. Mix sugar, starch, 4 tablespoons of fish sauce and half the garlic.
Mix into the meat. Wash and peel the mango and cut the flesh left and right of the core. Dice the flesh. Chop the peanuts. Heat oil in a pan and fry the flesh while stirring vigorously.
Add mango and remaining garlic and fry briefly. Season with remaining fish sauce and possibly a little salt. Let it cool down a little bit. Cut tomatoes into thin slices, cut lettuce into strips.
Put the lettuce in a bowl or on a plate and cover with tomato slices. Arrange beef and mango on top and serve sprinkled with peanuts.