Potato and Green Bean Salad

1 pound russet potatoes, cut into 1-inch cubes
2 cans green beans
1 cup finely chopped onion
½ cup chopped celery
¼ cup fresh parsley, or 1 Tbsp dried parsley
¼ cup canola or olive oil
¼ cup red wine vinegar
¼ tsp dried oregano
salt
pepper

Cook potatoes in salted water until almost done. Combine potatoes, green beans, onion, celery, parsley, oil, and vinegar and toss. Salt and pepper to taste. Serve at room temperature.