Brush or dip the avocado in the lemon juice, then mix with the tuna, cottage cheese, onion, pepper and mayonnaise in a bowl, and season well.

Cook the pasta shells in a large saucepan of boiling salted water for 10 - 12 minutes until just tender.

Drain and leave to cool. Stuff the shells with the filling and serve on a bed of crisp lettuce. This dish can be served either as a starter or a light lunch.

These stuffed pasta shells can be served as a tasty first course, with a light tomato dressing. Arrange the shells on individual plates. Stir 1 tablespoon tomato puree and a generous dash of Worcestershire sauce into 150 ml (1/4 pint) soured cream. Season to taste with garlic salt and pepper. Spoon this dressing over the pasta shells and serve with crisp toast or French bread.