In a medium bowl, combine the garlic, wine, broth, oil, salt, and red-pepper flakes. Add the shrimp and toss to coat. Set aside to marinate for 5 minutes.
Coat a large nonstick skillet with nonstick spray and warm over medium high heat. Add the bell bell pepper and cook for 1 minute to soften slightly. Add the shrimp and all but 1 tablespoon of the marinade. Cook for 2 minutes, or until the shrimp turn pink on the bottom. Turn the shrimp over and cook for 1 to 2 minutes longer, or until the shrimp are opaque.
In a cup, dissolve the cornstarch in the remaining 1 tablespoon marinade. Push the shrimp to the side of the pan and stir the cornstarch into the sauce is slightly thickened. Mix with the shrimp and serve immediately.