Begin by marinating the shrimp in the fish sauce, then set them aside.
Use a mortar and pestle to grind the peppercorns coarsely, ensuring they retain some texture. Coarsely chop the garlic, ginger, and red chili peppers.
Drain the shrimp from the fish sauce and coat them thoroughly with a mixture of flour and cornstarch. Ensure each piece of shrimp is evenly coated, then set them aside.
Heat a layer of oil in a pan, making sure it reaches 350 degrees Fahrenheit (175 degrees Celsius). Fry the shrimp for approximately 3 minutes, or until they turn golden brown. Remember to flip them halfway through the frying process. Fry the shrimp in smaller batches to ensure they cook evenly and become crispy. Once all the shrimp are fried, remove them from the oil.
Discard the excess oil from the pan. Add about 1 tablespoon of fresh oil and heat it. Once the oil is hot, add the chopped garlic and ginger. Sauté them until they start to brown, which should take around 2-3 minutes.
Add the chopped red chili peppers and sliced scallions to the pan and cook for an additional 1-2 minutes.
Gently combine the fried shrimp with the sautéed ingredients in the pan, stirring until everything is well incorporated. Remove the pan from the heat.
Finally, sprinkle the dish with the coarsely ground peppercorns and add coarse salt to taste. Garnish the dish with fresh cilantro leaves.
