Serves four persons: 

250 g cherry tomatoes 
1 onion 
1 Romaine lettuce 
250 g mushrooms 
6 tbsp vinegar 
salt, pepper 
6 tbsp olive oil

Method:
Clean lettuce and cut into strips. Clean tomatoes and cut in halves, clean mushrooms and cut into pieces. 
Mix with lettuce. 
Chop onions. Then mix with vinegar, salt and pepper, add oil. Pour over salad, and gently stir. 
Cooking time ca. 20 minutes, 
Each serving contains ca. 170 kcal / 710 KJ