Beef Stroganoff with Straw Potatoes

by Nadia Kim

12 servings

Mustard Sour Cream Sauce

• 6 tbspunsalted butter
• 6 tbspall-purpose flour
• 1 tbspdry mustard powder
• 3 cupsbeef stock
• ¾ cupsour cream

Beef

• 6 tbspunsalted butter
• 3small yellow onion
• 4.5 lbbeef tenderloin
• kosher salt
• black pepper

Straw Potatoes

• 4russet potatoes
• kosher salt
• 2 tbspparsley