Make the seasoning. In a bowl, add the salt, black pepper, sugar and chinese five spice powder. Stir to combine.
Trim the prawns. Cut and remove the long antenna as well as the sharp spine above the prawn's head. Turn the prawn over and cut off all of the legs.
Wash the prawns in cold water with a tablespoon of salt. Rinse to remove the salt.
Pat dry the prawns and sprinkle over the prawns 1/2 a teaspoon of the seasoning.
Coat the prawns with the cornstarch.
In a large pan, on medium-high add 1 cup of vegetable oil. Once the oil is hot, use a pair of tongs to carefully lay the prawns down into the pan in a single layer. When the bottom of the prawns is pink, turn the prawns over.
Remove from the pan once the prawns are golden brown and the prawn's tail has slightly curled up. Cook approximately 2 minutes on the first side and 1 minute on the other side.
Clean out the pan. Add 1 tablespoon of vegetable oil and 1 tablespoon of butter to the pan. Turn the heat on to medium and melt the butter.
Then toss in the minced garlic, sliced onions, and sliced jalapenos. Cook for 1 minute .
Add the prawns to the pan and sprinkle over the prawns 1/2 a teaspoon of the seasoning. Toss and cook for 2 minutes .
Serve with rice . To make the dip, squeeze a wedge or two of lemon juice into a small dipping bowl. Then add a pinch of salt and a pinch of black pepper.