All you have to do is to give it a nice long bath.Soaking the onion (large, sweet Vidalias work best) in cold water after you cut it will help the petals separate naturally instead of trying to ...
Slice the pepper finely and cut the onion into rings. Gently wash the salad rocket flowers, extra petals and leaves, and pat dry on kitchen towel. Incorporate all these ingredients in a salad bowl.