To make the clementine mayonnaise, put the egg in a hand blender with the clementine juice and some seasoning. With the motor running, gradually add the sunflower oil until you have a thick, emulsified mixture. Stir in the zest, season and set aside.
Prepare the salsa by mixing the mango, red onion and red pepper with 2 tbsp of the olive oil and the vinegar. Season.
Heat the remaining oil in a frying or griddle pan. Add the prawns and cook for 1-1½ minutes on each side or until just cooked through.
To serve, put a spoonful of mayonnaise in the bottom of each serving dish, sit the prawns on top, finish with a generous spoonful of mango salsa and sprinkle with the chopped coriander.