In a small bowl mash 1/2 medium sweet potato (4- to 5-oz.), cooked, with 1 to 2 Tbsp. cooking water, 1/8 tsp. salt, and pinch ground white pepper; set aside. In a small nonstick skillet cook 2 Tbsp. each chopped celery, carrot, and onion in 1 tsp. hot olive oil over medium heat for 5 to 7 minutes or until tender. Add 4 oz. pork tenderloin, cut into 1/2-inch cubes; cook for 2 minutes. Stir in 2 tsp. all-purpose flour, 1/4 tsp. crushed dried rosemary or 1/2 tsp. snipped fresh rosemary, pinch ground nutmeg. Stir in 1/4 cup reduced-sodium beef broth; cook about 2 minutes or until slightly thickened. Place pork mixture in a 10-oz. ramekin. Cover with mashed sweet potatoes. Broil 4 to 5 inches from heat for 3 to 5 minutes or until browned and bubbly.