In a mixing bowl, whisk together all sauce ingredients. Set aside.
In a second mixing bowl, toss shrimp with cornstarch, garlic powder, and pepper until coated well.
Heat oil in a large nonstick skillet over medium-high heat. Add shrimp in a single layer. Cook until golden on bottom and then flip over. When they turn opaque, add the sauce and cook for 1 to 2 minutes to thicken.