Sprinkle beef with salt and pepper; brown beef in batches in hot oil in a Dutch oven over medium-high heat. Remove beef from pan; set aside. Add celery and onion to pan; sauté 5 minutes. Add garlic; sauté 30 seconds. Return beef to pan; add broth and 1 3/4 cups water. Bring to a boil; cover, reduce heat, and simmer 1 hour. Add Yukon Gold potato to pan; cook, covered, 10 minutes. Add sweet potato; cook 20 minutes or until beef and potatoes are tender.
Combine flour and remaining 1/4 cup water, stirring until smooth. Gradually stir into meat mixture; cook, uncovered, 5 minutes. Stir in cream; cook 5 more minutes. Stir in cheese and, if desired, herbs; cook 1 minute or until cheese melts. Sprinkle each serving with freshly ground pepper just before serving.