Blanch the prawns in rapidly boiling water for one minute & put straight onto an ice bath. When the prawns are cold, peel & leave in fridge until serving.
For the mayonnaise – whisk the egg yolks, vinegar, mustard & seasoning together, then slowly add the oil, whisking continuously. When all the oil has been added, add some water to adjust the consistency and lemon juice to taste.
To make the vinaigrette – warm the oils together and pour over all the other ingredients in a sealable jar & store in the fridge shaking every day for one week.
To assemble – slice the mango, cucumber, spring onions & a little lettuce & mix with some vinaigrette & spoon into the bottom of your serving glass.
Divide the prawns between the four glasses & spoon over some Marie Rose sauce.
Serve with lime wedge & lightly dust with cayenne pepper.