Roasted Cauliflower with Onions and Fennel
Peer reviewed by UK recipe editorsAuthored by UK recipe editorsOriginally published 17 Jan 2026
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This roasted cauliflower with onions and fennel is a sophisticated vegan side dish that celebrates the natural sweetness of caramelised brassicas. By searing the vegetables in a frying pan before roasting, you develop a deep, savoury flavour and a golden colour that oven-roasting alone cannot achieve. The fragrant marjoram and whole garlic cloves infuse the oil, creating a Mediterranean-inspired aroma that pairs beautifully with the aniseed notes of the fresh fennel bulbs.
Whether you are looking for a healthy accompaniment to a Sunday roast or a substantial base for a plant-based warm salad, this recipe fits the bill perfectly. It is a versatile dish that works just as well served hot from the oven as it does at room temperature. For a complete meal, try serving it alongside some protein-rich pulses or a zestily dressed quinoa.
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Ingredients for Roasted Cauliflower with Onions and Fennel
1 medium head of cauliflower (about 575g), cored, cut into 1-inch florets
6 tablespoons olive oil, divided
2 medium onions (about 230g each), halved lengthwise, cut into 3/4-inch-wide wedges with some core still attached, peeled
2 fresh fennel bulbs (about 450g total), halved lengthwise, cut lengthwise into 1/2-inch-wide wedges with some core still attached
8 small garlic cloves, unpeeled
15 fresh marjoram sprigs
How to make Roasted Cauliflower with Onions and Fennel
Position rack in centre of oven; preheat to 218°C. Toss cauliflower and 2 tablespoons oil in large bowl. Heat heavy large skillet over medium-high heat. Add cauliflower and sauté until beginning to brown, about 5 minutes. Transfer cauliflower to rimmed baking sheet.
Add 2 tablespoons oil to same skillet. Add onion wedges. Cook until browned on 1 side, about 3 minutes. Using spatula, carefully transfer onions to baking sheet with cauliflower, arranging wedges browned side up. Add remaining 2 tablespoons oil to same skillet. Add fennel; sauté until fennel softens slightly and starts to brown, about 5 minutes. Transfer to same baking sheet. Scatter garlic and marjoram over vegetables. Sprinkle with salt and pepper. Roast until vegetables are caramelized, about 25 minutes. Serve hot or at room temperature.
Disclaimer
While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.
Article history
The information on this page is peer reviewed by qualified clinicians.
17 Jan 2026 | Originally published
Authored by:
UK recipe editors
Peer reviewed by
UK recipe editors

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