Saute onion and garlic in oil until onion is limp,about 10 minutes. Add the rest of ingredients and simmer for one minute,stirring constantly.The mixture will be quite thick.Let cool.Mix shrimp and cooled Sate' Sauce in a small bowl.Cover and let stand at room temperature for 30 minutes to one hour or refrigerate for 2 to 3 hours If you marinade in refrigerator,remove one hour before cooking.Save sauce. Skewer shrimp the long way so that they will lie flat on grill or broiler pan.Preheat broiler 5 to 10 minutes.Put shrimp on grill or in broiler and cook 10 minutes per side until each side is browned, turning only once. Using 2 tbsp. of marinade,mix with 1 1/2 cups of chicken stock.Bring to a boil and thicken with 1 tbsp. of cornstarch,mixed with 2 tbsp. of water.Stir in 1/4 cup sour cream and serve over rice.
