Remove and discard stalks from fennel bulb. Cut fennel bulb in half lengthwise; discard core. Chop fennel bulb to measure 1 1/2 cups.
Heat oil in a large nonstick skillet over medium-high heat. Add chopped fennel bulb and garlic; sauté 5 minutes or until tender. Add flour, and cook 1 minute, stirring constantly with a whisk. Stir in broth, vermouth, tomato sprinkles, and hot sauce, and bring to a boil. Reduce heat, and simmer 5 minutes or until thick, stirring occasionally. Add shrimp, and cook 1 minute. Keep warm.
Preheat broiler. Place polenta slices on a baking sheet coated with cooking spray. Sprinkle polenta with pepper. Broil 6 minutes or until lightly browned. Serve shrimp mixture over polenta.