Drain and rinse the 5 cans of beans.
Toss together the beans, red onion, celery, and green pepper in a large bowl.
In a smaller bowl, whisk together the salt, pepper, sugar, and red wine vinegar until the sugar is dissolved. Then gradually pour in the oil, whisking constantly until it all comes together.
Pour the dressing over the beans and veggies, and toss to coat. Cover and refrigerate, before serving. For best results, refrigerate at least 4 hours or overnight.
Toss the bean salad with the dressing once more before serving.
