Roast Lamb with Caper Sauce

The English Sunday joint with the white caper sauce that used to come with boiled mutton

Origin: England

From the journey of Caper.

Britain cannot grow a caper and has nonetheless welded them, permanently and almost exclusively, to one thing: sheep. The pairing came in through French cookery in the seventeenth and eighteenth centuries and had hardened into orthodoxy by the nineteenth. Boiled leg of mutton with caper sauce was so completely standard a dinner that it works as shorthand for respectable English eating in Victorian fiction, and Mrs Beeton gives the sauce, as does practically every English household manual after her. The sauce itself is a plain white one: butter and flour, let down with milk and some of the liquor the meat cooked in, and finished with a good spoonful of capers and a little of their vinegar. The logic is exactly the logic of every other dish in this journey. Mutton is fatty and its cooking liquor is bland, and capers supply salt and sharpness in a single move, without the sauce having to be built on wine or a long-reduced stock. That the British reached for it with a boiled joint rather than a roast one is simply a matter of what was on the table; boiling was the ordinary treatment for a large piece of mutton well into the twentieth century. Mutton has largely gone and boiling with it, so the dish survives in the form given here: a roast leg of lamb with the sauce served alongside in a jug. That is a fair modernisation rather than a betrayal, and it is how it appears on British pub and restaurant menus now. The sauce is also the standard accompaniment to poached skate and salmon, which is where a good many people meet it first. Britain deserves credit for the best of the caper substitutes as well. Nasturtium seed pods, picked green and pickled in spiced vinegar, were sold as poor man's capers and are genuinely good, with a peppery bite of their own; broom buds and marsh marigold buds had their advocates in the older books.

Ingredients

Lamb

2.2 kg leg of lamb, bone in
3 cloves garlic, cut into slivers
6 sprigs rosemary, broken into short lengths
2 tbsp olive oil
1 tsp sea salt
1 tsp freshly ground black pepper
400 ml lamb or chicken stock, for the tin

Caper Sauce

50 g unsalted butter
40 g plain flour
300 ml whole milk, warmed
200 ml strained cooking juices from the roasting tin, or stock
5 tbsp capers, rinsed, drained, and roughly chopped
2 tbsp caper vinegar, or white wine vinegar
3 tbsp flat-leaf parsley, finely chopped
2 tbsp double cream, optional

Method

Take the lamb out of the refrigerator an hour ahead. Heat the oven to 200°C fan, 220°C conventional.
Make small deep incisions all over the joint with the point of a knife and push a sliver of garlic and a short length of rosemary into each. Rub all over with the oil, salt, and pepper.
Set the lamb on a rack in a roasting tin and pour the stock into the tin beneath it. Roast at the high temperature for 20 minutes.
Reduce to 170°C fan, 190°C conventional, and roast for a further hour to an hour and ten for pink, or twenty minutes longer for well done. A thermometer in the thickest part should read 55°C for pink.
Lift the lamb onto a warm board, cover loosely with foil, and rest for at least twenty minutes. Strain the tin juices into a jug and skim off the fat.
Melt the butter in a saucepan over a medium heat, stir in the flour, and cook the roux for two minutes without letting it colour.
Add the warm milk a little at a time, beating smooth after each addition, then whisk in the skimmed cooking juices. Simmer gently for five minutes, stirring, until it coats the back of a spoon.
Take off the heat and stir in the chopped capers, the caper vinegar, the parsley, and the cream if using. Taste and adjust the vinegar; the sauce should be noticeably sharp.
Carve the lamb across the grain and serve with the caper sauce in a warm jug alongside, with new potatoes and greens.

Notes

For the original, boil rather than roast: simmer a 2 kg leg of mutton or lamb very gently in salted water with an onion, a carrot, and a bay leaf for about two hours, and use the cooking liquor in place of both the milk and the tin juices. It is a much-underrated way to cook a leg and gives a far better sauce. The sauce should be sharp. The commonest fault is timidity with the vinegar, which leaves it tasting of flour and milk with capers in it. Add the vinegar, taste, add more. Nasturtium seed pods, pickled in spiced vinegar, can replace the capers entirely and are the historic English substitute; they are hotter and more peppery and are excellent here. The same sauce is the classic English accompaniment to poached skate, to salmon, and to boiled bacon, and a spoonful of it is very good over plain boiled new potatoes on its own.

The Gastrographer

Name: Roast Lamb with Caper Sauce
Prep time: 20 min
Cook time: 1 h 30 min
Total time: 2 h 15 min
Yield: 6
Cuisine: England
Ingredients: 2.2 kg leg of lamb, bone in; 3 cloves garlic, cut into slivers; 6 sprigs rosemary, broken into short lengths; 2 tbsp olive oil; 1 tsp sea salt; 1 tsp freshly ground black pepper; 400 ml lamb or chicken stock, for the tin; 50 g unsalted butter; 40 g plain flour; 300 ml whole milk, warmed; 200 ml strained cooking juices from the roasting tin, or stock; 5 tbsp capers, rinsed, drained, and roughly chopped; 2 tbsp caper vinegar, or white wine vinegar; 3 tbsp flat-leaf parsley, finely chopped; 2 tbsp double cream, optional

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Journey Point Map Key

Ingredient originTrade or transit route

Became a culinary stapleColonial / trade control