Potato salad, old fashioned

Ingredients

• 3 lb. Red potatoes
• 3 eggs, hard boiled
• 1/4 c. buttermilk
• 1 c. mayonnaise
• 2 Tbs. Dijon mustard
• 2 Tbs. whole grain mustrad
• 1/2 c. dill
• 1/2 c. celery
• 1/2 c. red onion
• salt and pepper