Pat lamb dry with paper towels; season with 1 tsp. salt and 1/2 tsp. pepper. Heat oil in a large skillet over high heat. Cook lamb in hot oil 3 to 4 minutes on each side or until browned. Place lamb on a rack in a broiler pan.
Combine breadcrumbs and next 5 ingredients in a small bowl. Combine mayonnaise and mustard in a small bowl. Brush mustard mixture over meaty top side of lamb racks; pat herb mixture evenly over mustard to adhere.
Bake at 350° for 20 to 25 minutes or until a thermometer inserted into thickest portion registers 145° (medium rare). Let stand 10 minutes. Garnish platter, if desired. Cut each rack into double chops.
Note: You'll want to ask your local butcher to french the racks of lamb for you, trimming them down to clean bones and small succulent eyes of meat that will be easy to cut apart after roasting.