This slow cooker 3-ingredient mustard corned beef is exactly how my grandfather swore the March classic should be made—simple, unfussy, and all about the meat. With just a corned beef brisket, its seasoning packet, and a generous blanket of grainy yellow mustard, the slow cooker does all the work. The result is a tender, sliceable roast with a rosy-pink interior and a shiny mustard glaze resting in a clear, savory broth. It’s perfect for busy weeknights or St. Patrick’s Day when you want that traditional flavor without hovering over the stove all day.
Serve the sliced mustard corned beef with boiled or roasted potatoes and steamed cabbage or green beans for a classic plate. Spoon a little of the clear cooking broth over the meat to keep it juicy, and offer extra mustard on the side for anyone who likes an extra kick. Leftovers make wonderful sandwiches on rye or soft rolls with a slice of cheese and a pickle. A simple green salad or buttered egg noodles also pair nicely if your family isn’t big on cabbage.
Slow Cooker 3-Ingredient Mustard Corned BeefServings: 6
Ingredients
3–4 pound corned beef brisket, flat cut, including seasoning packet
1/2 cup water
1/2 cup yellow grain mustard (or coarse ground yellow mustard)
Directions
Place the corned beef brisket in the bottom of a large slow cooker, fat side up. Open the seasoning packet that comes with the corned beef and sprinkle all of it evenly over the top and sides of the meat.
Pour the water into the bottom of the slow cooker, around the brisket, being careful not to rinse off the seasoning on top. The water should just cover the bottom of the crock and come slightly up the sides of the meat, creating a shallow bath for the brisket to braise in.
Spread the yellow grain mustard over the top of the corned beef in an even layer, like you’re frosting a cake. Try to cover the entire surface so it forms a flavorful glaze as it cooks.
Cover the slow cooker with the lid and cook on LOW for 8–10 hours, or until the corned beef is very tender when pierced with a fork but still holds together enough to slice. Avoid lifting the lid during cooking so the heat and moisture stay trapped inside.
Once done, carefully transfer the corned beef to a cutting board, letting any excess broth drip back into the slow cooker. Tent loosely with foil and let it rest for 10–15 minutes so the juices settle and the meat stays moist.
Slice the corned beef against the grain into thin or medium slices, depending on your family’s preference. Spoon some of the clear broth from the slow cooker over the sliced meat to keep it glossy and juicy, and serve warm with extra mustard if desired.
Variations & Tips
If your family prefers a stronger mustard flavor, mix an extra tablespoon or two of mustard into the cooking broth before starting the slow cooker, or brush more mustard on during the last hour of cooking. For a milder version for picky eaters, scrape off some of the mustard before slicing and serve their portions with just a light drizzle of broth. You can also use a mix of yellow grain mustard and Dijon for a slightly sharper, more grown-up taste, or swap in all coarse ground yellow mustard if that’s what you have on hand. If you like your meat very shreddable for sandwiches, let it go closer to the 10-hour mark; for neater slices, start checking around 8 hours. Save the leftover broth—strain it and use it to moisten leftovers, cook potatoes, or as a base for a simple soup with chopped leftover corned beef and vegetables. Leftover slices are wonderful reheated gently in a bit of the broth, or served cold on sandwiches for easy next-day lunches.
