These Roasted Potatoes and Onions are the only roasted potato recipe you will ever need. Every bite is infused with fresh rosemary and whole grain mustard. They’re roasted for a long time so the potatoes get super crispy and the onions caramelize. The flavors are earthy, slightly sweet, and mustard-spicy-tangy, and your whole family will love them! Best of all, they’re easy enough to make on a casual weeknight, and fancy enough for a dinner party, Thanksgiving, or other holiday meal.
I think I could seriously eat a whole batch of these in one sitting. If they look familiar to you, they’re adapted from Ina Garten’s recipe. When my mother-in-law made them for dinner one night, I knew I needed to make a version for Bowl of Delicious. While Ina’s recipe is very good (I mean, she’s Ina Garten- of COURSE it’s good!), I made just a few tweaks to the recipe and process to highlight the roasted potatoes a bit more and ensure even roasting.
One of the things I always do when roasting vegetables is mix them in a large bowl with all the ingredients, THEN transfer to a baking sheet. So many recipes require spreading them out on a baking sheet, drizzling with oil, and adding the seasonings on top. I find that mixing in a bowl before ensures a much more even, thin coating on the vegetables and enables you to use less oil than you would when drizzling. When I add oil on top of veggies directly in the baking sheet, I find it pools up on the baking sheet, causing scary splattering in the oven.
If it looks like you are using a lot of onions, GOOD. It may seem like a lot at first, but don’t worry: they cook down substantially while roasting and they are potentially the most delicious part of this whole recipe, since they get wonderfully browned and caramelized in the oven.
Here are some other tips when making these roasted potatoes and onions.
- Cut the potatoes into pieces no bigger than a half an inch. This means more surface area to get deliciously browned and toasty tasting.
- Use PLENTY of salt. Potatoes are bland, and need a lot of it.
- Make sure you use a sturdy baking sheet (I swear by the classic Nordic Ware half baker’s sheet– it doesn’t buckle under high heat and nothing sticks to it!).
- Finally, make sure you stir the potatoes around only once- no more than that. You want to give the vegetables time to brown and their liquids to evaporate in between stirs. If you stir them too frequently, they will get recoated in the liquid, which will cause them to stick to the pan more easily and not crisp up quite as much.
Other easy potato side dish recipes:
- Everything Bagel Crispy Smashed Potatoes
- The BEST Twice-Baked Potatoes
- Nepalese Potato Salad
- Warm Potato Salad with Bacon and Arugula
Roasted Potatoes and Onions with Rosemary and Mustard
- Mix all ingredients in a large bowl (make sure you salt liberally!).
- Spread evenly on a sturdy rimmed baking sheet.
- Roast at 425 degrees for approximately 1 hour, stirring once halfway through, until potatoes are browned and onions crispy.
- It's important to not overcrowd the pan. Use two baking sheets if needed, or cut the recipe in half.
- The onions can cook a bit more than desired if sliced too thinly, and also I find if I'm using an electric oven (for some reason, gas never burned the onions for me, but when I switched to an electric one I had to keep a closer eye on it). If you're concerned about this or need to troubleshoot burnt onions, try slicing the onions a bit thicker or add them to the sheet pan a little ways into cooking the potatoes so they aren't in there the whole time.
Nutrition Information Disclaimer
The provided nutrition information is my best estimate and does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. I use an automatic API to calculate this information. Feel free to calculate it yourself using one of these tools: