- For tian:
- 1 1/2 pounds tomatoes, cut crosswise into 1/4-inch-thick slices
- 1 pound onions, thinly sliced
- 1 (1 pound) eggplant, cut crosswise into 1/4-inch-thick slices
- 4 large garlic cloves, chopped
- 1 1/2 teaspoons dried oregano, crumbled
- 2 pounds boiling potatoes, peeled and cut into 3/4-inch-thick slices
- 1 teaspoon salt
- For lamb:
- 1 (7 pound) leg of lamb (aitchbone removed by butcher)
- 3 large garlic cloves, thinly sliced
- 1/4 cup fresh lemon juice
- 1 teaspoon dried oregano, crumbled
- Toss half of tomato slices with onions, eggplant, garlic, oregano, potatoes, salt, and pepper to taste in a large bowl. Transfer to an oiled shallow 3-quart casserole, spreading evenly. Arrange remaining tomato slices on top. Roast, uncovered, in middle of oven 30 minutes.
- Prepare lamb: Trim lamb of all but a 1/4-inch layer of fat. Cut small slits all over lamb with a sharp small knife and put a slice of garlic into each slit. Rub lamb with some lemon juice and season with oregano, salt, and pepper.
- After tian has been roasting 30 minutes, put lamb on top of vegetables. Roast in middle of oven 30 minutes, then reduce temperature to 350 degrees F.
- Continue roasting, basting meat with cooking juices (baste with remaining lemon juice during last 30 minutes of roasting) until a thermometer inserted into thickest part of meat (do not touch bone) registers 135 degrees F for medium-rare, about 1 1/2 hours. Transfer meat to a cutting board, cover tian with foil, and let meat stand 15 minutes before carving. Spoon off any excess fat from tian and discard. Serve tian with lamb.