The Best Bean Salad

Ingredients

• 1 can (1 lb.) kidney beans, drained and rinsed
• 1 can (1 lb.) Great Northern beans, drained and rinsed
• 1 can (1 lb.) green beans, drained and rinsed
• 1 can (1 lb.) yellow wax beans, drained and rinsed
• 1/2 cup onion, minced
• 1/2 cup cider vinegar
• 1/2 cup vegetable oil
• 1/2 tsp. salt
• 1/2 cup sugar
• 1/2 tsp. freshly ground pepper