Ingredients and preparation:

Soak 1/4 cup sliced red onion in cold water and leave it there for 10 minutes, then drain.
Mix the onion with 2 cups of Hearts of Palm sliced, 1 cup of sliced celery and chopped parsley.
Add 3 tablespoons of lemon juice and 3 tablespoons of olive oil.
Season the mix with salt and pepper.
Serve over arugula.