Place asparagus and tomato halves in an 11 x 7inch baking dish. Drizzle vegetables with oil; toss gently to coat. Place vegetables on a grill rack coated with cooking spray. Grill asparagus 3 minutes on each side; grill tomato 1 minute on each side. Return asparagus and tomato to dish. Sprinkle vegetables with salt, pepper, and lemon rind.