Ensure the raw shrimp are completely dry by patting them with paper towels, which helps the coating adhere properly. Toss the shrimp in a mixture of cornstarch, black pepper, and ½ teaspoon of salt until each piece is evenly coated. Shake off any excess cornstarch.
In a small bowl, combine the remaining salt, black pepper, and sugar to create the finishing seasoning mix.
Heat cooking oil in a pan or wok over medium-high heat. Once the oil is hot, carefully add the coated shrimp in a single layer. Fry for 2 to 3 minutes, flipping them halfway through, until they are golden and crispy, and fully cooked. Remove the shrimp and place them on a paper towel-lined plate to drain excess oil.
Pour off most of the oil from the pan, leaving about a tablespoon. Add the minced garlic and sliced jalapeño peppers to the pan over medium heat. Sauté for 30 to 60 seconds until fragrant and the peppers are softened, being careful not to burn the garlic.
Sprinkle the prepared seasoning mix evenly over the shrimp and sautéed ingredients, tossing everything together to combine.
