These oven baked 4-ingredients Guinness onion roasted potatoes are my cozy, Midwest kitchen take on a classic Irish pub-style side. The dark stout and sweet onions roast down into a glossy, caramelized glaze that clings to the potatoes, just like the kind you’d find alongside a proper roast in Dublin. I first made this for my husband, who grew up in Dublin, and he said it tastes just like home—simple ingredients, nothing fussy, just good potatoes, onions, and Guinness slow-roasted until everything is deeply browned and full of flavor.
Serve these Guinness onion roasted potatoes hot, straight from the foil-lined baking sheet, with any hearty main: roast chicken, grilled sausages, pot roast, or a simple pan-seared steak. They’re also lovely with roasted carrots or steamed green beans to brighten the plate. A spoonful of sour cream or plain Greek yogurt on the side is great for kids who like to dip, and a little grainy mustard or extra drizzle of pan juices makes them feel like a pub-style side for the grown-ups. Leftovers reheat well in a skillet for breakfast alongside eggs and bacon.
Oven Baked 4-Ingredients Guinness Onion Roasted PotatoesServings: 4
Ingredients
2 lb small Yukon Gold or red potatoes, scrubbed and quartered
2 large yellow onions, peeled and thickly sliced
1 cup Guinness or other Irish stout beer
3 tbsp neutral oil (such as canola or vegetable oil)
1 1/4 tsp kosher salt, divided
1/2 tsp freshly ground black pepper (optional, but recommended)
Nonstick cooking spray or extra oil, for greasing the foil
Directions
Preheat your oven to 400°F (200°C). Line a large rimmed baking sheet with aluminum foil, then lightly grease the foil with nonstick cooking spray or a thin film of oil. This helps the potatoes and onions caramelize without sticking too badly.
Prep the potatoes and onions: Scrub the potatoes well and pat them dry, then cut them into quarters (aim for even-sized pieces so they cook at the same rate). Peel the onions and slice them into thick wedges or half-moons, about 1/2-inch thick, so they can hold up to the long roasting time.
Toss everything together: In a large bowl, combine the quartered potatoes and sliced onions. Drizzle with the 3 tablespoons of oil, sprinkle with 1 teaspoon of kosher salt and the black pepper (if using), and toss until everything is lightly and evenly coated.
Spread on the baking sheet: Pour the potato and onion mixture onto the prepared baking sheet, spreading it into a mostly even single layer. A little overlap is fine, but try not to crowd them too much or they’ll steam instead of roast.
Add the Guinness: Slowly pour the 1 cup of Guinness over the potatoes and onions, distributing it across the pan. You want a shallow layer of liquid on the foil—this will simmer, then reduce into that rich, dark glaze you’re after. Gently shake the pan to settle everything in place.
Start roasting: Place the pan on the middle rack of the preheated oven and roast for 25 minutes without stirring. During this time, the Guinness will bubble and start to soak into the potatoes and onions.
Stir and continue roasting: After 25 minutes, carefully pull the pan out, give the potatoes and onions a good stir, scraping up any bits that are starting to brown on the foil. Return the pan to the oven and roast for another 20 minutes.
Encourage caramelization: After the second roast, stir again, making sure to flip the potatoes so new sides are in contact with the foil. Sprinkle the remaining 1/4 teaspoon of kosher salt over the top. Continue roasting for 15–20 more minutes, stirring once more if needed, until the potatoes are tender all the way through, the onions are deeply browned, and most of the liquid has reduced to a thick, dark, sticky glaze.
Finish and serve: When the potatoes are fork-tender and the onions look caramelized with a rich brown sheen, remove the pan from the oven. Let everything sit on the hot pan for 3–5 minutes; the glaze will thicken slightly as it cools. Use a spatula to gently lift the potatoes and onions from the foil, scraping up as much of the dark, sticky goodness as you can, and transfer to a serving dish or bring the pan right to the table for a more casual, family-style feel.
Variations & Tips
For picky eaters, you can reduce the onions to 1 large onion and slice it more thinly so it blends in with the potatoes, or even roast a small corner of the pan with just plain oiled potatoes for kids who prefer things simple. If you’d like a slightly sweeter, more kid-friendly version, add 1 to 2 teaspoons of brown sugar or honey when you toss the potatoes and onions with oil; this helps the glaze caramelize and balances the bitterness of the stout. For a stronger Dublin-style pub flavor, sprinkle 1 teaspoon of dried thyme or 1 tablespoon of chopped fresh rosemary over the potatoes before roasting. To keep this recipe closer to four main flavor ingredients, think of the potatoes, onions, Guinness, and oil as the core, and treat salt and pepper as basic pantry seasonings rather than extra ingredients. If you need it alcohol-free, you can use non-alcoholic stout or a mix of 3/4 cup beef or vegetable broth plus 1/4 cup apple juice; it won’t taste exactly like Guinness, but it will still give you a rich, savory glaze. Food safety tips: Guinness and other beers are safe to cook with as the alcohol mostly cooks off at this temperature and time, but if you are serving someone who needs to fully avoid alcohol, choose a non-alcoholic stout or the broth mixture instead. Always wash and scrub potatoes well to remove any dirt, and trim away green spots or sprouts before cooking, as those can be bitter and should not be eaten. Use a sharp knife and a stable cutting board when quartering potatoes and slicing onions, and keep fingers tucked in to avoid slips. Because the baking sheet and glaze get very hot, use thick oven mitts and allow the pan to cool briefly before letting children help themselves. Leftovers should be cooled to room temperature within 1–2 hours, then stored in an airtight container in the refrigerator and eaten within 3–4 days; reheat in a hot oven or skillet until steaming all the way through.
