Three Bean Salad

Name: Three Bean Salad
Ingredients: ¼ cup olive oil; ¼ cup cider vinegar; 1 to 2 tablespoons sugar; ½ teaspoon dry mustard; Salt and freshly ground black pepper to taste; 1 cup cooked red kidney beans, drained; 1 cup cooked fresh green beans, drained; 1 cup cooked fresh lima beans, drained; ½ medium red bell pepper, cored, seeded, and finely chopped (generous 1/3 cup); 2 scallions, finely chopped (about ¼ cup)