Keto Sunday roast with cauliflower mash, pancetta sprouts and mushroom gravy
A low‑carb roast dinner: succulent beef with garlic-herb butter, creamy cauliflower mash, pancetta Brussels sprouts and a rich mushroom gravy.
This is a properly indulgent low‑carb Sunday roast that keeps all the roast‑dinner joy without the carbs. Think buttery, garlicky beef, pillowy cauliflower mash and pancetta‑browned sprouts — all fully keto friendly.
It’s perfect for a chilly weekend when you want something impressive but not fiddly: most of the work is hands‑on searing and a couple of simultaneous pans. The gravy finishes the plate rich and glossy without any flour, so you stay keto while still getting that comforting roast dinner feel.
Ingredients
- 1 kg beef sirloin joint
- 10 g sea salt — divided
- 5 ml black pepper — freshly ground, divided
- 30 ml olive oil
- 100 g unsalted butter — divided between meat, mash, mushrooms and gravy
- 6 garlic cloves — crushed and divided
- 6 sprigs fresh thyme sprigs
- 4 sprigs fresh rosemary sprigs
- 800 g cauliflower — broken into florets
- 60 ml double cream
- 50 g cream cheese
- 400 g Brussels sprouts — trimmed and halved
- 150 g pancetta — diced
- 300 g chestnut mushrooms — quartered
- 15 g flatleaf parsley — finely chopped
- 500 ml beef stock — low-salt if preferred
- 150 ml red wine — optional for gravy
- 15 ml Dijon mustard
- 0 g xanthan gum — optional, very small amount to thicken gravy
Equipment
- roasting tray
- digital meat thermometer
- food processor or blender
- large frying pan
- saucepan
Instructions
Remove the beef from the fridge and pat dry with kitchen paper. Season all over with half the sea salt and half the black pepper. Leave at room temperature for 30 minutes.
Preheat the oven to 220°C fan/240°C conventional. Meanwhile make the garlic-herb butter: mash together 40 g of the unsalted butter with 2 crushed garlic cloves, 3 thyme sprigs and 2 chopped rosemary sprigs; set to one side.
Heat a large frying pan over a high heat with the olive oil. When very hot, sear the beef on all sides until a deep brown crust forms (about 2 minutes per side). Transfer to a roasting tray and smear the garlic‑herb butter over the top; tuck the remaining thyme and rosemary around the joint.
Roast on the top shelf at 220°C fan/240°C conventional for 10 minutes to colour, then reduce the oven to 180°C fan/200°C conventional and roast for a further 35–40 minutes for medium‑rare (target internal temperature 55°C) or until you reach your preferred doneness.
While the beef roasts, prepare the cauliflower mash. Put the cauliflower florets in a saucepan with cold salted water, bring to the boil and simmer until very tender, 12–15 minutes. Drain thoroughly and return to the pan for a minute over a low heat to dry out.
Blitz the drained cauliflower in a food processor with 30 g unsalted butter, the double cream and the cream cheese until smooth. Season to taste with the remaining sea salt and black pepper and keep warm.
Prepare the sprouts and pancetta: heat a large frying pan over a medium heat, add the diced pancetta and fry for 4–5 minutes until it renders and begins to crisp. Add the halved Brussels sprouts and 2 crushed garlic cloves, fry for 6–8 minutes until the sprouts are caramelised and tender. Stir in half the chopped parsley and season.
In a separate pan, melt 15 g unsalted butter and sauté the chestnut mushrooms with a pinch of sea salt for 6–8 minutes until brown. Stir in the remaining chopped parsley and keep warm.
When the beef reaches the target temperature, transfer to a board and very importantly rest for 15 minutes, loosely covered with foil.
While the beef rests, make the gravy. Pour off all but 1 tbsp fat from the roasting tray into a saucepan, place over a medium heat, add the red wine and scrape the tray to lift any browned bits. Add the beef stock and Dijon mustard, simmer and reduce by about one‑third, 8–10 minutes. Whisk in 15 g unsalted butter and 30 ml double cream to finish. If you want a thicker gravy, whisk in the xanthan gum very gradually, a pinch at a time, until it coats the back of a spoon.
Carve the beef thinly across the grain. Serve slices with a generous scoop of cauliflower mash, a portion of pancetta Brussels sprouts and sautéed mushrooms. Spoon the warm mushroom gravy over the beef and scatter the remaining parsley.
Tips
- Take the beef out of the fridge in plenty of time — an initial 30‑minute rest at room temperature helps it cook more evenly.
- Dry the cauliflower well after boiling and briefly return to the pan to evaporate excess moisture; otherwise the mash will be watery.
- Use a digital meat thermometer: 55°C for medium‑rare, 60°C for medium. Remove the joint a few degrees early — carryover cooking will finish it while resting.
- If you haven’t got xanthan gum, reduce the gravy more slowly to concentrate flavour; less gravy is still better than a thin one.
Substitutions
beef sirloin joint → pork loin (1 kg), roast to an internal temperature of 63°C for juicy pork
Noticeably differentpancetta → streaky smoked bacon (150 g), will be smokier and slightly saltier
Stays closecauliflower → celeriac (800 g) for a slightly earthier mash, slightly higher carbs
Noticeably different
Nutrition
Per serving · estimated
- 1120
- Calories
- 70 g
- Protein
- 18 g
- Carbs
- 85 g
- Fat
- 6 g
- Fibre
- 8 g
- Sugar
- 900 mg
- Sodium
FAQ
Can I prep this in advance?
You can make the cauliflower mash and sauté the mushrooms up to 24 hours ahead and refrigerate. Reheat gently and add a splash of cream to loosen. Cook the beef on the day for best texture.
How do I make the gravy without wine?
Skip the red wine and reduce an extra 100 ml of beef stock with a little balsamic vinegar (5–10 ml) to add acidity and depth.
Is xanthan gum necessary?
No — it’s optional. It thickens quickly and requires a tiny amount. If you prefer not to use it, reduce the gravy further until it’s glossy and coats the back of a spoon.
Can I swap the beef for chicken or lamb?
Yes. Lamb shoulder or leg works well but will need longer, slower roasting. Chicken requires shorter cooking times and a different resting temperature — adjust with a thermometer.
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