Cook pasta according to package directions, omitting salt and fat.
Sprinkle pork with 1/4 teaspoon salt and pepper. Melt 1 1/2 teaspoons butter in a large nonstick skillet coated with cooking spray over medium-high heat. Add pork; sauté 4 minutes or until pork loses its pink color. Remove pork from pan; keep warm.
Add broth to pan; cook 30 seconds. Add 1 teaspoon butter, 1/4 teaspoon salt, onion, and mushrooms; cook 8 minutes or until lightly browned. Remove from heat.
Combine sour cream, dill, Dijon mustard, and flour in a small bowl. Add pork and sour cream mixture to pan; stir well. Serve pork mixture immediately over noodles. Garnish with dill sprigs, if desired.