Place the lamb chops on a plate. Sprinkle with 3 tablespoons of oil and lemon juice. Peel garlic. Finely chop 2 clove of garlic and sprinkle with rosemary over the chops. Marinate the chops for about 20 minutes.
Peel and wash the potatoes, cut them into pieces and cook them in boiling salted water for about 15 minutes. Wash tomatoes, dab dry, clean and cut in half. Cut the rest of the garlic clove into thin slices.
Heat 1 tablespoon of oil in a frying pan. Roast the slices briefly in it, take them out. Fry the lamb chops for 2 minutes on each side, remove and keep warm. Add the tomatoes to the frying fat and braise for approx. 3 minutes.
Season with salt and pepper. Drain the potatoes. Add butter and milk and mash. Season to taste with salt and nutmeg. Arrange in a bowl and sprinkle with garlic slices. Arrange lamb chops and tomatoes on plates.
Garnish with lemon wedges and rosemary. Serve with mashed potatoes.