Peel the shrimps, except for the tail end, and remove the black intestine. Wash the prawns and pat them dry. Peel and chop garlic and onion. Chop the chillies and mix with lime juice, sugar and fish sauce.
Fry the prawns in hot oil while turning for 5-7 minutes. Remove from the pan. Fry the onion, garlic and chilli in the frying fat until golden brown. Add the lime-sugar-mixture and let it boil down syrupy for about 10 minutes.
Add the prawns again and heat them up in the sauce. Arrange prawns with lime slices or pieces and sliced garlic on a plate. Add sauce extra.