Seafood Cocktail Salad

4 scallops, dark beards removed
100 g/4 oz white fish
100 g/4 oz peeled prawns
shredded lettuce leaves
8 tomatoes, skinned and quartered
Sauce:
120 ml/4 fl oz reduced-calorie mayonnaise
1 dessertspoon tomato puree
1 teaspoon chopped basil
salt
freshly ground black pepper

Place the scallops and white fish in a saucepan. Poach in the minimutn of water for about 4 to 5 minutes until tender. Drain and cool