Greek-Style Tuna Salad

1 (5 ounce) can chunk light tuna in water, drained

1 tablespoon chopped red onion

2 teaspoons prepared Greek vinaigrette salad dressing (such as Kraft®)

3 pitted Kalamata olives, chopped

1 tablespoon crumbled feta cheese

Mix the tuna, onion, salad dressing, olives, and feta cheese together in a bowl.