1. Preheat grill to 350º to 400º (medium-high) heat. Remove silver skin from tenderloin, leaving a thin layer of fat.
2. Sprinkle pork with 1 tsp. salt and 1/2 tsp. pepper. Combine mustard and next 4 ingredients. Rub mustard mixture on pork; cover and let stand 10 minutes.
3. Preheat oven to 450º. Cut squash and zucchini into 1/2-inch slices; cut into half moons. Toss with 1 tsp. olive oil and remaining 1 tsp. salt and 1/4 tsp. pepper. Place on an aluminum foil-lined jelly-roll pan, and bake 20 minutes or until tender.
4. Meanwhile, grill pork, covered with grill lid, 10 to 12 minutes on each side or until a meat thermometer inserted into thickest portion registers 155°. Remove from grill; cover with foil, and let stand 10 minutes. Slice pork, and serve with squash medley. Sprinkle with thyme.