Place the minced steak into a bowl with the crushed garlic, soy sauce, egg, salt and pepper and mix well. Form the mixture into 4 equal sized burger. Grill the burgers over a medium heat for 4 to 5 minutes on both sides. Just before the burgers are ready, place a slice of cheese on top and allow it to melt. Grill the pineapple and onion slices over a high heat until soft and slightly browned.
For the sauce
Simply stir the mayonnaise, soy sauce, honey and cayenne together.
To assemble
Arrange salad leaves onto the toasted brioche rolls, top with sauce, burgers, cheese, slices of radish, grilled onion, and pineapple before serving.