Pat the shrimp dry with a paper towel and set aside.
In a small bowl, whisk together soy sauce, hoisin sauce, cornstarch, and water. Set aside.
Heat vegetable oil in a large skillet over medium-high heat. Add the shrimp and cook for 3 minutes per side, until pink and cooked through. Remove from the skillet and set aside.
In the same skillet, add a little more oil if necessary. Add the minced garlic and grated ginger, and sauté for 2 minutes until fragrant.
Add the snow peas to the skillet and cook for 3 minutes, stirring occasionally, until they are tender-crisp.
Return the shrimp to the skillet and pour the sauce over them. Stir to coat the shrimp and snow peas with the sauce, cooking for another 1-2 minutes until the sauce has thickened slightly.
Serve hot over rice or noodles, garnished with green onions if desired.