1 bone-in leg of lamb (1.5-2kg)
6 cloves garlic (1 split, the rest copped)
1kg russet potatoes, peeled and very thinly sliced
Salt and pepper, to taste
1 tablespoon, fresh thyme
2 large onions, very thinly sliced
5 medium tomatoes (500g), cored and thinly sliced
2/3 cup dry white wine
1/3 cup olive oil
Preheat oven to 200C. Rub bottom of a large gratin dish with split garlic clove. Arrange the potatoes in a single layer.
Season with salt, pepper and some of the thyme and chopped garlic. Layer sliced onions on top; repeat the seasonings. Layer tomatoes on top and season with salt, pepper and remaining garlic and thyme.
Drizzle top with wine and then the oil. Trim thicker portions of fat from the leg of lamb. Season meat with salt and pepper. Place lamb on a sturdy cake or oven rack directly on top of the gratin dish. Roast, uncovered, for about 1 hour (for rare lamb).
Turn lamb every 15 minutes, basting with liquid from the dish underneath. Remove from oven and let lamb sit 20 minutes before carving.
To serve, carve lamb into thin slices and arrange on a serving platter, with vegetable gratin alongside.