– 1½ cup mayonnaise – ¼ cup capers, minced – ½ small red onion, minced – 1 cup canned tuna in water, (drained), shredded – 2 small radishes, grated – ½ teaspoon salt (or more, to taste) – ½ teaspoon freshly cracked black pepper (or more, to taste) – 1 tablespoon minced fresh parsley, dill, or chives (or minced green onion)