Peel, stone and slice a ripe avocado and use
instead of the prawns. Toss it in a little lime
juice to stop it discolouring.
Spread the tortilla chips over a large plate. Stir
most of the coriander through the soured cream
or crème fraîche, squeeze in the juice of one
lime quarter and season to taste. Spoon over
the tortilla chips, then scatter over the rest
of the ingredients and remaining coriander.
Serve at once.