Wash shrimp in cold water and cut off long whiskers and sharp point on the head with scissors and dry with paper towel.
In small bowl, combine salt, pepper, and sugar and set aside. If you're using the sichuan pepper corns, lightly toast and then using mortar and pestle, crush coarsely and add to seasoning mixture.
Heat large wok or deepfryer with cooking oil to high, about 350 degrees. Dredge the shrimp in the rice flour to get a light coating, shaking off excess. fry the shrimps in small batches until nicely pink/red and crispy, about 3-4 minutes. Remove and drain.
Heat another large wok/pan with a bit of cooking oil. When oil is hot, add garlic and then chiles and scallions. Quickly stir-fry the veggies for a minute or so and add the shrimp and sprinkle about 1/2-1 ts seasoning mixture. Continue to stir fry and make sure seasoning coats well, for another minute. Transfer to serving plate and serve immediately. Sprinkle on additional seasoning according to taste.
best served with Rice or Ginger Noodles..................