Open sandwich with prawns, tomato and lime mayonnaise

300g pack frozen cooked and peeled prawns, defrosted and drained
2 tbsp lime juice
2 large tomatoes, halved, deseeded and finely chopped
100g fat free natural fromage frais
3 level tbsp extra light mayonnaise
Salt and freshly ground black pepper
8 slices wholemeal bread (from small 400g loaf)
75g pack watercress

1. In a bowl, mix the prawns with the lime juice, tomatoes, fromage frais and mayonnaise and season to taste.

2. Place 2 slices of bread on each plate and top with a small handful of watercress. Divide the prawn topping between the bread and serve immediately.