Slow-Roasted Andalusian-Style Lamb and Potatoes

Preheat oven to 350 °F. Combine garlic, thyme, and 2 tablespoons salt in a small bowl. Using your fingertips, rub mixture until it resembles wet sand (larger pieces of garlic will remain); set aside. Crush bay leaves. Combine half of potatoes with 1 tablespoon oil and 1 crushed bay leaf in a large roasting pan; season with salt and pepper and toss to coat. Spread out potatoes in a single layer. Place lamb on top of potatoes and rub with garlic mixture. Layer tomatoes, onions, remaining 3 crushed bay leaves, and remaining potatoes around and up sides of lamb, seasoning with salt and pepper and drizzling with remaining 6 tablespoons oil as you go (lamb will be nearly covered). Add wine to pan; cover tightly with foil. Roast until lamb is very tender, 3-4 hours. Remove foil and increase oven temperature to 425 °F. Roast, turning lamb halfway through, until lamb is golden, 20-25 minutes longer. Let rest in roasting pan for 15-20 minutes. DO AHEAD: Lamb can be roasted 2 days ahead. Cover and chill. Reheat before continuing. Pull meat from bones in large chunks; discard bones and fat. Place meat and vegetables on a platter. Skim fat from surface of cooking juices in pan. Spoon some cooking juices over lamb and vegetables and serve remainder alongside.