In a large bowl, whisk together the lemon juice, olive oil, and Dijon mustard. Add salt and pepper to taste.
Add beans, onion slices, and olives; toss to combine.
Place prepared salad in the refrigerator for about 2 hours before serving to allow the flavors to blend properly.
Makes 6 to 8 servings.
Bean and Olive Salad Recipe: https://whatscookingamerica.net/salad/beanolivesalad.htm