Wash the iceberg lettuce and cut as desired. Put the salad in a bowl. Now cut the tomatoes, radishes, peppers, mushrooms and cucumber and add to the salad.
Cut the red onion into rings (be careful, only use the outer rings - the others are too hot). Put the onion rings on the salad and spread the dressing over them. Of course, you can also use a different dressing of your choice.