Grind the salt, black pepper and Szechuan peppercorns in a pestle and mortar.
Mix the salt and pepper mixture with the sugar and set aside until required.
Rinse the prawns (shrimp) under cold running water and pat dry with absorbent kitchen paper.
Heat the oil in a preheated wok. Add the prawns (shrimp),chilli, ginger and garlic and stir fry for 4-5 minutes, or until the prawns (shrimp) are cooked through.
Add the salt and pepper mixture to the wok and stir –fry for 1 minute.
Transfer to warm serving bowls and garnish with spring onions (scallion).
Serve hot with prawn (shrimp) crackers.