To make the Marie Rose sauce, blend
the mayonnaise with the ketchup and
a couple of shakes of Tabasco in a bowl.
Trim the bases of the lettuce hearts,
discard the outer leaves and separate
the leaves – they need to be about 10cm
long and you want about 24 in total.
Reserve the tiny hearts for another salad.
Wash the prawns and pat dry between
double layers of kitchen paper. Toss in
a bowl with the olive oil, lemon juice,
parsley and a little seasoning.
Lay the leaves out on serving plates,
cup-side up. Drop several prawns into
each. Dollop ½ tsp sauce on top, then
scatter over some mustard and cress.
These can be prepared 1 hr in advance,
in which case cover with cling film and
set aside in a cool place.