Peel and butterfly the prawns, put in a bowl and pour over the juice of 2 limes with a tablespoon of wine vinegar and the passion fruit pulp. Leave to cook in the citrus for 30 minutes or until the prawns are pink and opaque. Larger prawns can take longer.
Place all the ceviche sauce (tiger milk) ingredients in a blender and process until smooth.
Place the prawns and marinade in a bowl and pour in the ceviche sauce and stir.
Garnish with half a finely sliced red onion, finely sliced cucumber, coriander and (optionally) slices of fresh jalapeños for heat.
Serve with small flour/ corn tortillas fried in oil for 30 seconds on each side.