Combine water and cornstarch in small saucepan, mixing until cornstarch dissolves. Stirring constantly, bring mixture to a boil, then reduce heat to medium and cook until thickened-about 2 minutes. Remove from heat and stir in ginger and garlic. Set aside to cool to room temperature.
In blender, combine cornstarch mixture and pecans, vinegar, soy sauce, sugar, sesame oil, and red pepper flakes; blend until smooth puree. Set aside while preparing shrimp.
Prepare a hot charcoal fire or preheat a gas grill. Skewer shrimp or arrange on grill topper and cook over grill, turning occasionally, until the shrimp are pink and lightly browned. To serve, divide Spicy Pecan Sauce among serving plates, pooling it on one side. Place four shrimp on top of each pool of sauce. (Alternately, the sauce can be used for dipping with the shrimp served around it.)
Nutrition information per serving-199 calories; 9g protein; 9g carbohydrates; 1g fiber; 14g fat; 1g saturated fat; 42mg cholesterol; 244mg sodium.