Step 1

In a small saucepan, combine vinegar, sugar, oil, garlic, 1 teaspoon salt, and 1/2 teaspoon pepper. Cook over medium heat until sugar dissolves, about 3 minutes. Remove from heat and pour into a bowl with a cover that is large enough to hold the salad.

Step 2

Stir in green beans, wax beans, kidney beans, red onion, and parsley and toss until evenly coated. Cover and refrigerate at least 4 hours or overnight to blend flavors.

Step 3

Remove from refrigerator at least 30 minutes before serving and bring to room temperature.