Get out a large mixing bowl.
Put the wax beans, green beans, kidney beans, black-eyed peas, chickpeas, cucumber, corn, onion, and chopped green onion in the bowl.
Give them a good toss for mixing
In another bowl, mix mustard, celery, parsley, oregano, salt, vinegar, and sugar
Stir until the sugar is wholly incorporated. You can heat this slightly to make the blending quicker.
Pour the dressing over the beans
Blend them together, making sure everything is well-coated
Refrigerate overnight before serving