Heat a large nonstick skillet over medium-high heat. Sprinkle lamb chops with 1/8 teaspoon salt and 1/8 teaspoon black pepper. Coat pan with cooking spray. Add lamb to pan; cook 2 minutes on each side or until lightly browned. Remove lamb from pan. Add remaining 1/8 teaspoon salt, remaining 1/8 teaspoon black pepper, onion, and garlic to pan; sauté 2 minutes.
Place fennel seeds in a heavy-duty zip-top plastic bag; seal. Crush seeds with a rolling pin. Add seeds, capers, and tomatoes to pan; bring to a boil. Return lamb to pan. Cover, reduce heat, and cook 6 minutes or until desired degree of doneness.