Slow-roasted lamb shanks with roasted garlic sauce, celeriac puree and broccolini

Grease the lamb shanks with olive oil and season generously with salt, pepper and mustard powder.

Cut the top off two whole garlic heads so every clove is exposed; put them in the roasting tray under the shanks so they do not burn, and coat everything with oil and seasoning.

Brown under the broiler a few minutes, flip, and broil another couple of minutes, about five minutes in all; without a broiler, use the maximum baking temperature or skip this.

Arrange evenly in the tray, add no liquid, seal tightly with foil and slow roast at 285F / 140C until fall-apart tender and the garlic is golden and soft, about four hours.

Peel the celery root, slice thin, stack the slices and cut into matchsticks, then cross-cut to a rough dice.

Melt butter in a large pan and cook the celeriac over high heat, stirring constantly, about 10 minutes, until reduced by about a third and just starting to brown.

Add milk just to cover, turn to low, cover and simmer gently until soft; the milk curdles. Simmered about an hour.

Pour off and reserve the liquid (mostly whey); puree the solids in the food processor until smooth, thinning with reserved liquid if needed.

Season the puree with salt, a little cayenne and a squeeze of lemon, which also keeps it from browning.

Move the shanks to a baking sheet and take the garlic out to cool.

Boil the meat juice in the roasting tray until the sound turns from boiling to frying and most of the water is gone, then pour off the rendered fat, keeping the browned solids.

Squeeze the roasted garlic from its skins into the tray, deglaze with the reserved celery whey (or white wine or water), scrape up the solids and mash the garlic to a smooth paste.

Optionally strain through a sieve into a heat-safe bowl; this is purely cosmetic.

Melt in butter slowly with little or no bubbling so the emulsion does not break; taste, and add the other half lemon for acid. The sauce should taste a little too acidic on its own.

Return the shanks to the oven at about 400F / 200C to reheat and crisp the surface a few minutes.

Steam the broccolini a couple of minutes until barely fork tender; drain, melt butter in the pan, return the broccolini with a pinch of salt and toss.

Reheat the puree in the microwave and serve the shanks with the puree, broccolini and sauce.