Potato Salad with Sour Cream

Ingredients

• 6 cups diced cooked potatoes -
• 1 cup chopped celery -
• 1/2 cup chopped seeded peeled cucumber -
• 1/2 cup chopped green pepper -
• 1/4 cup sliced green onions -
• 6 hard-boiled large eggs -
• 1 cup sour cream -
• 1/2 cup mayonnaise -
• 1 tablespoon prepared mustard -
• 4 teaspoons white vinegar -
• 1-1/2 teaspoons salt -
• 1/2 teaspoon pepper -
• 1 teaspoon celery seed, optional -