Guinness Onion Butter Pork Roast: 5-Ingredient Crockpot Dinner

This slow-cooker pork sirloin roast is the ultimate set-it-and-forget-it dinner. With just four ingredients—pork, pearl onions, Guinness stout, and a whole stick of salted butter—it transforms into a rich, savory, melt-in-your-mouth meal.

The dark stout adds malty depth, the butter enriches the sauce, and the onions become sweet and tender. After 8 hours on low, you'll have fork-tender pork that's perfect over mashed potatoes or on sandwiches.

This recipe is a celebration of simplicity. A boneless pork sirloin roast is nestled into a slow cooker with pearl onions, a bottle of Guinness stout, and a stick of salted butter. That's it.

The slow cooker does all the work, turning the pork into shreddable perfection while the onions soften and the juices meld into a glossy, buttery sauce. It's the kind of meal that feels special but requires almost no effort. Serve it over mashed potatoes or with crusty bread to soak up every last drop.

Ingredients

Why this recipe works

Slow cooking is the secret to this dish. The low, steady heat of the crockpot breaks down the connective tissue in the pork sirloin, turning a lean cut into tender, shreddable meat.

The long cooking time also allows the flavors of the Guinness and butter to penetrate the pork, creating a deeply savory result that tastes like it simmered all day—because it did.

The combination of stout and butter is a classic pairing that elevates the humble pork roast. The stout's roasted, slightly bitter notes balance the richness of the butter, while the pearl onions add a gentle sweetness. As the pork cooks, it releases its juices, which mingle with the stout and butter to form a natural pan sauce that needs no thickening.

Notes and substitutions

Pork sirloin roast is a lean, relatively inexpensive cut that works beautifully in the slow cooker. If you can't find it, pork shoulder or butt is a great substitute—just plan for a slightly longer cooking time. Look for a roast that's about 3 1/2 pounds, and trim any large fat caps if you prefer.

Guinness draught stout is the beer of choice here, but any dark stout or porter will work. The alcohol cooks off during the long simmer, leaving behind a malty, slightly bitter flavor.

For a non-alcoholic version, use beef broth with a splash of balsamic vinegar. Salted butter is key—it seasons the meat and sauce as it melts. If using unsalted, add a pinch of salt.

• pork sirloin roast: pork shoulder or pork butt (boneless) works well; increase cook time by 1-2 hours if needed.
• Guinness draught stout: Any dark stout or porter beer can be used; for a non-alcoholic version, use beef broth with a splash of balsamic vinegar.
• pearl onions: Frozen pearl onions (thawed) or 2 cups of chopped yellow onion can be substituted.
• salted butter: Unsalted butter plus 1/4 teaspoon salt.

Equipment

• 6-quart slow cooker
• Measuring cups
• Large spoon
• Cutting board
• Knife