Season lamb shanks with salt and pepper. In large skillet, heat oil over medium high heat. Brown each shank on all sides. Combine butter and thyme leaves, baste shanks. Remove shanks from pan.
Add broth, garlic and onions. Simmer for 6 minutes. Stir, deglazing pan. Arrange lamb shanks in large roasting pans. Pour in broth mixture. Add thyme sprigs. Cover with foil. Braise in 325°F oven for 3 - 1⁄2 to 4 hours.
Remove shanks, cover and keep warm. Strain liquid and skim off fat. In pan, combine broth from shanks and artichokes, add lemon juice. Cook and reduce.
Warm artichoke wedges in broth just before serving. To serve: Place each shank in large shallow bowl with broth, onions and artichoke wedges. Sprinkle with tomato pieces, fava beans and dill.