Slow Cooker Beef Stroganoff

Step 1: Pat the beef dry, then sprinkle it with all the salt and pepper.

Step 2: Heat 1 tablespoon of oil in a large heavy-bottomed pot or skillet over high heat. Add the beef in a single layer without crowding it and brown all over, about 4 minutes. Remove the beef and repeat with the remaining beef, adding more oil as needed.

Step 3: Let the pot cool a little, then return it to the stove. Melt half the butter and cook the garlic and onion for 3 minutes, until softened.

Step 4: Sprinkle the flour over the surface and stir. Add the mustard and stir; the mixture will look gluey, but it will dissolve.

Step 5: While stirring, pour in about half the beef stock and mix until the flour dissolves. The mixture will thicken quickly to a gravy-like consistency. Switch to a whisk if needed to remove lumps. Add the remaining stock, stir well while scraping the bottom of the pot, and bring to a simmer. Continue with your chosen cooking method.

Step 6: Slow cooker: Transfer all the liquid to the slow cooker. Add the beef and cook on LOW for 8 hours or HIGH for 5 hours.

Step 7: Stovetop: Add the beef to the pot and cover with a lid. Adjust the heat to low or medium-low so the stew simmers gently. Simmer for 2 hours, checking at 1.5 hours, until the beef falls apart easily.

Step 8: Instant Pot: Skip the flour and follow the gluten-free option in the notes. Cook on high pressure for 40 minutes, using the same method as for the slow cooker.

Step 9: Other pressure cookers: Cook on high pressure for 40 minutes, using the same method as for the slow cooker.

Step 10: Melt half the butter in a large skillet over high heat. Add half the mushrooms and cook until almost golden, about 3 minutes. Add half the garlic, salt, and pepper, and cook until golden. Remove the mushrooms and repeat with the remaining butter, mushrooms, and garlic.

Step 11: Mix the sour cream with 1.5 cups of liquid from the slow cooker, then gently stir it into the stew; the beef is delicate.

Step 12: Gently stir in the mushrooms.

Step 13: Serve over noodles, pasta, or mashed potato, sprinkled with chives.