Whisk the soy sauce, garlic, ginger powder, white pepper, honey, and chili paste (if using) in a small bowl.
Warm the vegetable oil in a large nonstick skillet over medium-high heat. Once the oil is hot, add the shrimp and cook until pink, about 1 minute per side. (We just want to get some color on the shrimp here—it doesn’t need to be fully cooked on the inside just yet!)
Remove the shrimp from the skillet and set aside. Pour the prepared sauce into the skillet, and let it come to a simmer over medium heat.
Combine the cornstarch and water in a small bowl to create a slurry. Slowly mix this into the heated sauce, and let it all simmer together until you have a thick, sticky sauce, 2 to 4 minutes.
Toss the shrimp back into the pan. Cook until the shrimp is opaque and fully cooked, about 3 minutes more. Garnish with the sliced scallions and toasted sesame seeds.