Oven-Baked Whole Red Onions with Thyme and Garlic: Easy Side Dish Recipe

As an experienced home cook who's hosted countless dinner gatherings, I recently prepared this standout side dish for our cooking club. Featuring hearty winter vegetables, the menu highlight was whole red onions roasted to perfection with fresh thyme and garlic. Simple yet impressive, this recipe delivers sweet, caramelized flavors that pair beautifully with any meal. Here's how to make it.

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Oven-Baked Red Onions with Thyme: The Ultimate Side Dish

This straightforward recipe requires minimal prep and just 40 minutes in the oven. Plan for one medium red onion per person—larger ones work best for optimal results. Below are the ingredients and step-by-step instructions, refined from years of testing in my kitchen.

Ingredients for Red Onions with Thyme and Garlic

• 1 red onion per person
• Fresh thyme
• Garlic (half a clove per onion)
• Butter
• Salt

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How to Prepare Whole Oven-Baked Onions

One onion per person suffices as a generous side; scale up if needed for heartier appetites.

• Preheat oven to 180°C (350°F).
• Soften butter to room temperature (microwave briefly if needed, but avoid melting).
• Peel the red onions.
• Trim the bottom slightly for stability.
• Cut a deep cross into the top with a sharp knife, stopping short of the base so the onion holds together in four quarters.
• Thinly slice peeled garlic cloves.
• Insert garlic slices into the cross cuts, adding 2 thyme sprigs per onion.

• Place onions in a bowl, stuff butter into the cuts, and sprinkle with salt.
• Roast for about 40 minutes until tender and golden.

Perfect Pairings for Roasted Red Onions

We enjoyed these alongside oven-roasted winter vegetables, bone-in ham, and creamy celeriac purée—a true feast that wowed our group.