Dry roast the salt, pepper, and five spice pepper in a pan. Remove from the heat, allow to cool, then combine with the sugar and mix well. Set aside. In a deep fry pan or wok, bring the oil to 350 degrees F. Dust the prawns in the flour and fry 2 prawns at a time in order to keep the oil at a constant high heat. Cook the prawns about 1 minute. Remove the prawns and place on a rack set over a baking sheet or on kitchen paper towels to absorb the excess oil. Repeat with the remaining prawns and set aside. Carefully remove the fry pan or wok from the heat. Place a separate fry pan over medium heat, and add a dash of oil. Next add the garlic, red shallots, chile, and spring onion, and cook until fragrant. Now add the fried prawns, tossing as you sprinkle the salt, pepper, and five spice mixture, making sure you coat the prawns well. Remove the prawns and serve with lime.