Cook the mushrooms in a non-stick pan without oil, stirring for 10 minutes to drive off all the moisture.
Process the onion, courgette, carrot and nuts in a food processor until beginning to bind together.
Stir in the mushrooms, bread crumbs, parsley, yeast extract and seasoning to taste. With the oatmeal shape into four burgers. Chill.
Cook the burgers in a non-stick frying pan with very little oil or under a hot grill for 10 minutes, turning once, until the burgers are cooked and golden brown.
Serve hot with a crisp salad.
Servings: 4