– 1½ cup mayonnaise – ¼ cup capers minced – ½ red onion (medium), minced – 1 cup canned tuna or salmon (drained of water), shredded – 2 radishes (small), grated – ½ teaspoon salt (or more, to taste) – ½ teaspoon pepper (or more, to taste) – 1 tablespoon parsley minced, or chive, or dill