Peel the onion, garlic and ginger, dice everything very finely. Clean and wash the chilli and chop very finely with the seeds. Remove the outer leaves from the lemon grass. Cut the stalks lengthwise and chop very finely.
Clean, wash and cut the spring onions into rings. Wash the coriander, shake dry and pluck off the leaves.
Cut the shrimps lengthwise at the back and remove the intestines. Rinse shrimps and pat dry. Mix starch, salt and pepper on a flat plate.
Heat the frying oil in a wok or pan with a high rim to a height of approx. 1 cm. Turn the shrimps in the starch, then tap lightly. Fry half the shrimps in the wok for 1-2 minutes on each side.
Take out, let it drip off on kitchen paper. Fry the rest of the prawns as well. Discard the frying oil, wipe out the wok.
Heat 3 tablespoons of oil in a wok. Fry the onion, garlic, ginger, chilli and lemongrass for about 1 minute until golden brown, stirring continuously. (Attention! The garlic can quickly darken and then tastes bitter.) Stir in sugar and fish sauce.
Turn off the stove. Quickly stir in the prawns, spring onions and coriander. Serve with jasmine rice.