Perfect Roast Lamb Leg With Gravy

This Roast Lamb Leg with Gravy features a secret umami butter rub for deep savory flavor. Served with creamy celeriac mash and fresh mint sauce, it creates the ultimate Sunday roast centerpiece.

Prep Time 5

Cook Time 2 30

Resting time 10

Total Time 2 45

Equipment

Large roasting tray
Digital meat thermometer
Sieve

Ingredients

The Lamb & Vegetables

▢ 2.5-3 kg Leg of lamb
▢ 4 Red onions
▢ 2 bulbs of garlic

Herby Butter

▢ 100 g Unsalted butter at room temperature
▢ 1/2 bunch Fresh thyme
▢ 1/2 bunch Fresh rosemary

Gravy

▢ 3 tbsp Plain flour
▢ lug Port quantity not specified
▢ 1 litre Hot organic chicken stock

Celeriac Mash

▢ 1 Celeriac
▢ 1 kg Potatoes
▢ Extra virgin olive oil
▢ 1 Whole nutmeg for grating

Mint Sauce

▢ 1 big bunch Fresh mint
▢ 2 tbsp Red wine vinegar
▢ 1 tbsp Soft brown sugar

Instructions

Prep the Lamb and Build Flavor

Heat the oven to 220ºC/425ºC/gas 7. You want it properly hot so the fat starts sizzling on contact.
Score the lamb all over, aiming for lines about ½cm apart and 3mm deep, just through the fat, not into the meat. This boosts browning on the fat cap.
For the herby butter, whiz the 100g butter with thyme and rosemary until it looks flecked and green, then season it well. If using the anchovy twist, blend them in now.

Set Up the Tray and Roast

Halve the unpeeled red onions and scatter them in a large roasting tray. Separate and bash the unpeeled garlic cloves, then tuck them among the onions to form a sturdy vegetable trivet.
Smear the herby butter over every inch of the lamb, pushing it into the scoring so it bastes from the top down. Sit the lamb directly on the onions and garlic.
Roast for 10 minutes for every 450g, plus 20 minutes at the end. The fat should be bronzed and fragrant, and the tray should smell of rosemary and sweetness.

Cook the Mash, Rest the Lamb, Make the Gravy, Finish with Mint

While the lamb roasts, peel and chop the celeriac into 3cm chunks, and peel and chop the potatoes into 2cm chunks. Boil in salted water for 15 to 20 minutes until tender. Drain, steam dry, then mash with a good lug of olive oil, grated nutmeg, sea salt, and black pepper.
When the lamb is done, lift it out and rest it for at least 10 minutes. Set aside half a red onion for the mint sauce, then squash the remaining onions in the tray.
Set the tray over high heat, stir in the flour, then pour in a lug of port and the hot chicken stock. Scrape up the sticky browned bits, stir until glossy and thickened, then pass through a sieve.
Finely chop the mint and the reserved onion half (skinned). Stir with vinegar and sugar until sharp-sweet. Serve everything together.

Notes

The Anchovy Twist: Blend 4 to 6 anchovy fillets into the herby butter. They dissolve during roasting, adding deep umami flavor to the meat and gravy without tasting fishy.

Temperature Guide: Use a meat thermometer for precision. Rare is 52°C (125°F), Medium-rare is 57°C (135°F), and Medium is 63°C (145°F). Remove the lamb slightly early as the temperature rises during resting.

Gravy Depth: A 'lug' of port is roughly 60-80ml. If you don't have port, red wine or Madeira works well to perfume the pan.

Carving Tip: Slice along the bone to release the large muscles, then cut thin slices across the grain to ensure every bite is tender.

Nutrition information is estimated based on common ingredients and serving sizes and may vary.

Keyword Bone-in lamb, Leg of lamb, Roast lamb gravy, Roast Lamb Leg with Gravy, Sunday roast

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