Sweet leeks are a heavenly partner to lamb and in this simple casserole, you only have a handful of ingredients to prepare before the dish goes into the oven to cook quietly on its own. If possible, make it the day before you plan to eat, giving the flavours time to develop.
1.1kg boned lamb shoulder, diced into 2" pieces
400-450g leeks, trimmed and sliced
4 cloves garlic, peeled and crushed
1 heaped tbsp nigella seeds
1 heaped tbsp wholegrain mustard
500ml chicken or lamb stock
Large handful of flat leaf parsley, chopped
Preheat the oven to 160C / Gas Mark 3
Heat a little oil in a large casserole pan and brown the diced lamb in batches, seasoning with salt and pepper as you go. Make sure you brown the pieces on all sides, to give plenty of flavour, adding more oil as you need it. Keep to one side.
Once all of the lamb is browned, add the sliced leeks to the same pan and cook for 2-3 minutes over a moderate heat, stirring. Add the garlic and nigella seeds and turn the heat down, to cook the leeks as gently as possible. Cover with a lid and cook for 10 minutes, being careful not to let the leeks stick to the bottom of the pan and burn. Stir and cook for a further 5 minutes.
Return the lamb to the pan along with the wholegrain mustard, parsley and stock. Stir well, season with salt and pepper and bring to a gentle simmer. Return the lid to the pot and place in the centre of the oven for 1 ½ hours.
At this point, taste the casserole, checking to see if the lamb is tender. If not, return to the oven for a further 30 minutes.
Finally, taste and adjust the seasoning if needed. Serve with mashed or new potatoes.