Trim away any sharp or pointy areas of shrimp. Using a scissor, carefully cut the back side of the shrimp with the shell on. Devein, rinse and set aside.
In a pan over low heat, toast the white peppercorns for 2 to 3 minutes so until fragrant. Using a mortar and pestle or spice grinder, grind into a fine powder. *Skip if using pre-ground white pepper Season the shrimp with salt and white pepper. Mix well. Next, add cornstarch and mix until fully coated.
In a deep pot, heat neutral oil over medium heat to 375 F / 190 C. Add the shrimp, making sure not to overcrowd the pot. You may need to work in batches. Drain on a wire rack or on a bed of paper towels.
In a wok, heat up 2 tbsp oil and toss in the minced garlic. When they've slightly browned, add the chopped peppers and stir fry for 1 minute.
Toss in the fried shrimp and season with salt and white pepper to taste. Stir together to mix well.
Garnish with scallions and enjoy!