Roasted Cauliflower and Onions, an easy baked vegetable combo that’s great as a side or a topping for salads and bowl. Only 5 ingredients and 30 minutes!

roasted cauliflower and onions on a white plate with a gold fork

Love cauliflower? Love onions? Roast them together! This roasted vegetable recipe is super simple and flexible, and it’s great for meal prep. Enjoy it as a side dish or topping for salads and bowls!

👉 Ready to learn how to make roasted onions and cauliflower together? Let’s do it!

cauliflower, an onion, and bowls of olives, salt, and pepper on a white table
Ingredients: cauliflower, onions, garlic, olive oil, salt, pepper

🥣 How to make (step-by-step photos)

1️⃣ Step One: Preheat oven and prep vegetables

First, preheat your oven to 400 degrees F (200 C), then prep the vegetables with a quick wash before cutting them.

  1. To cut onions: Cut stems from the onion and then make a slice around the outside to remove the outer layer. Then cut the onion into rounds, or in half and then into slices.
  2. To cut cauliflower: Cut off the hard stem from the head, then slice the head in half and remove the cauliflower florets.

👉 Cutting tip! We like to roasted vegetables like cauliflower and onions into similarly sized pieces so they're easier to eat, have similar cooking times, and for extra crunch.

cut cauliflower florets on a cutting board with an onion
Cut cauliflower and onions

2️⃣ Step Two: Season and add to baking sheet

Next, place the cut cauliflower and onions on a roasting or sheet pan.

Toss the veggies with olive oil until completely coated. Season with sliced garlic, as well as salt and pepper to taste.

👉 Roasting tip! We like to keep the vegetables separated on the roasting pan. Cauliflower can a bit take longer to bake and you can easily scoop the roasted onions off the pan when they’re done and keep cooking the potatoes.

cauliflower florets and onions slices on a baking sheet before roasting
Add to a baking sheet and season

3️⃣ Step Three: Bake vegetables in the oven

Now it’s time to roast the vegetables in the oven until they begin to brown, which takes about 25 minutes depending on your oven.

To make sure the onions and cauliflower cook evenly, stir the vegetables halfway throughout cooking. If the onions are cooking faster, remove them to a plate and continue to cook the cauliflower until it’s done.

When the veggies are done cooking, take them out of the oven. If using as a side dish, serve them immediately. You can also let them cool and serve on top of salads or bowls.

a white side dish of roasted onions and cauliflower on a table

💡 Seasoning ideas

We kept it simple with garlic, salt, and pepper in this recipe, but here are some seasoning ideas:

  • Add a squeeze of citrus: squeeze a bit of lemon or lime over the top of vegetables for an acidic kick
  • Cumin and paprika: add a dash of cumin and paprika for a deep, earthy flavor
  • Paprika, chili powder, and cayenne: spice up this dish with paprika and chili powder, then sprinkling a little cayenne pepper on top

♻️ Sustainable kitchen + cooking tips

We care about reducing food waste here at Fork in the Road, and we know you do too! Here are tips for making this recipe sustainably:

Take advantage of cauliflower and onions season! The best time to make both onions and cauliflower are when they are both in season! Cauliflower is available in late summer and early fall, while onions are available for most of the year. Click here to find out when they are in season in your area.

Save your scraps! Both cauliflower leaves and onions peels are actually edible! Add leaves to your salads or soups and add onion peels to your next homemade food scrap vegetable broth.

a close up photo of baked cauliflower and onions on a white plate

👉 More roasted cauliflower and onion recipes

Can't get enough cauliflower and onions? Try our other easy roasted vegetable recipes:

Roasted Cauliflower and Onions

Roasted Cauliflower and Onions, an easy baked vegetable combo that’s great as a side or a topping for salads and bowl. Only 5 ingredients and 30 minutes!
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  • 1 large onion, yellow, white, or red
  • 1 head cauliflower
  • 2 cloves garlic, sliced thin
  • 2 tablespoons olive oil
  • 1 pinch salt and pepper


  • Prep oven: Preheat the oven to 400 degrees (200 C)
  • Prep vegetables: Cut stems from the onion and then make a slice around the outside the onion to remove the top layer. Then cut the onion into rounds, or in half and then into slices. Cut the stems from the cauliflower and remove the leaves. Wash the head of cauliflower, then slice in half and then use a knife to cut the florets from the thick white center.
  • Roast vegetables: Arrange the cut cauliflower florets and onion slices on a roasting pan and drizzle with olive oil, tossing the vegetables to completely cover with oil and sprinkle with sliced garlic, salt, and pepper. Place sheet pan in the oven and roast for 25 minutes, stirring partway through to brown on all sides.
  • Serve vegetables: Remove pan from oven, arrange vegetables on a plate and serve as a side dish or let cool and use as a salad or bowl topping.


  • Tools needed: sheet pan, knife set, cutting board
  • Prep ahead: Wash and cut vegetables ahead of time to reduce prep time before cooking. If serving cold on salads or bowls, you can make this recipe up to three days ahead of time.
  • Leftovers and storage: Leftover onions and cauliflower should be stored in an airtight container in the refrigerator for up to 3-4 days. For best taste and texture, do not freeze and reheat.
  • Nutrition notes: Nutrition information is estimated for only ingredients in the recipe, not the additional spice options given. This simple roasted vegetable recipe is a good source of fiber, vitamin A, vitamin C, and potassium.

Nutrition Information

Serving: 1serving, Calories: 115kcal, Carbohydrates: 11g, Protein: 3g, Fat: 7g, Saturated Fat: 1g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 5g, Sodium: 55mg, Potassium: 491mg, Fiber: 4g, Sugar: 4g, Vitamin A: 1IU, Vitamin C: 73mg, Calcium: 43mg, Iron: 1mg