Preheat oven to 350°.
Sprinkle lamb with 1/4 teaspoon salt and 1/8 teaspoon black pepper. Place lamb in a shallow roasting pan coated with cooking spray. Add 1/2 cup water. Bake at 350° for 1 hour and 15 minutes. Remove lamb from oven; cool slightly. Remove meat from bones and chop; discard bones, fat, and gristle. Add 1 cup water to roasting pan, scraping pan to loosen browned bits. Place a zip-top plastic bag inside a 2-cup glass measure. Pour drippings into bag; let stand 10 minutes (fat will rise to the top). Seal bag; carefully snip off 1 bottom corner of bag. Drain drippings into a bowl, stopping before fat layer reaches opening; discard fat. Reserve lamb broth.
Heat oil in a large nonstick skillet over medium-high heat. Add bell pepper and onion; sauté 1 minute. Stir in thyme, cloves, and garlic; sauté 1 1/2 minutes. Add tomato paste; cook 5 minutes or until paste begins to brown, stirring constantly. Stir in wine, celery, crushed red pepper, 1/4 teaspoon salt, and 1/8 teaspoon black pepper. Bring to a boil; cover, reduce heat, and simmer 30 minutes.
Combine 1 tablespoon water and cornstarch, stirring with a whisk. Add lamb, reserved lamb broth, and cornstarch mixture to bell pepper mixture. Bring to a boil; cook 1 minute or until thick, stirring occasionally.