Lamb used to be the exclusive product of spring, starting with the winter-born lambs of southern England, followed by Welsh and Scottish lambing as weather permitted. Now imports mean it is available all year round. Lamb technically remains lamb up to a year old, when it becomes mutton, though connoisseurs insist that mutton is from an animal aged six to ten years. Less than 5 per cent of lambs are allowed to live past one year, which explains why mutton is so difficult to find.
Having tracked down your leg of mutton, the day before you want to eat it put it in a very large pan, cover it with cold water and bring to the boil. Skim, lower the heat to a bare simmer and add the celery, 2 of the carrots, the onions and black peppercorns. Poach for 2 hours and remove from the heat, then leave overnight in the poaching liquid.
Next day, skim any fat from the surface of the poaching liquid, remove the vegetables and discard. Return to the boil and skim again. Add a little salt, then lower the heat again to simmer and cook for a further 1 hour. Add the potatoes and remaining carrots to cook with the mutton for the last 25–30 minutes.
To make the caper sauce, mix the butter with the flour and mustard powder to make a firm paste (a beurre manié). Ladle
© 1998 Alastair Little and Richard Whittington estate. All rights reserved.