Combine the first 3 ingredients; sprinkle evenly over lamb. Place lamb in a heavy-duty zip-top plastic bag. Add garlic and sherry; seal bag, turning to coat. Marinate in refrigerator 3 hours, turning occasionally.
Prepare grill or broiler.
Place lamb on grill rack or broiler pan coated with cooking spray; cook 5 minutes on each side or until desired degree of doneness. Serve with lime wedges, if desired.