Add the vinegar, oil, sugar, salt, and pepper to a small bowl and whisk until combined. Set aside.
Next, trim both the green and wax beans and cut them into bite-size pieces, about 1”.
Add the green and wax beans to a large pot of boiling salted water for 2 to 3 minutes and then flash chill them in an ice bath.
Drain the green and wax beans completely and add them to a bowl with the kidney beans, garbanzo beans, celery, peppers, onion, parsley, dressing, salt, and pepper, and mix until combined. Serve.
