In a small bowl, mix together shrimp and fish sauce. Set aside to marinate.
Use a mortar and pestle to grind the peppercorns* and salt coarsely, leaving some larger pepper chunks.
Coarsely chop the garlic, ginger, and red chili peppers.
Drain shrimp and pat dry. Toss shrimp with flour and cornstarch to coat evenly. Set aside.
In a medium skillet on medium high heat, heat a layer of oil in a pan (about ¼ inch), making sure it reaches 350°F.
Fry shrimp in small batches, leaving space between each one for approximately 3 minutes, or until they turn golden brown on both sides, flipping after about 90 seconds. Once shrimp are cooked, remove from the oil and place on a paper towel lined plate.
Discard excess oil from the pan. Add 1 tablespoon fresh oil and heat on medium heat. Once hot, add garlic and ginger. Sauté just until they start to brown, about 2-3 minutes (be careful not to burn them).
Add chopped red chili peppers to the pan and cook for 1-2 minutes. Add sliced green onions to the pan and cook for 2 more minutes.
Add the fried shrimp to the pan and gently combine with the sautéed mixture, stirring until everything is well incorporated. Remove from the heat.
Sprinkle the dish with the coarsely ground peppercorns and salt mixture to taste. Garnish with fresh cilantro leaves and serve immediately
Notes
*Substitute peppercorns with about ½ teaspoon freshly ground black pepper, or to taste.
Fry shrimp in smaller batches to ensure they cook evenly and crisp well.