Devein shrimp. Sprinkle 1 Tbsp potato starch over the shrimp, rub together well, and rinse out a few times. Remove moisture by patting dry with a paper towel. In a bowl, mix shrimp, 1 Tbsp potato starch, Sake, and salt together. Let sit for 10 minutes.
Mix ingredients of Chili sauce in a medium bowl. Set aside.
In a wok or frying pan, heat 1 Tbsp oil. Cook prepared shrimp until the color changes, turning a couple of times. Remove shrimp from the pan.
In the same pan, add another 1 Tbsp oil with ginger, garlic, and onions, and cook at medium heat to be fragrant. Add Chili sauce mixture, and cook until the sauce gets slightly thicker. Add shrimp and cook for a minute. Serve immediately.
