Slow Cooker Beef Bone Gravy

A slow cooker on low sits at about 90C, which happens to be the ideal temperature for stock and is very hard to hold on a hob. Set it going after dinner and you wake up to a pot of beautiful clear stock. The only downside is you cannot skim easily, so roast the bones cleanly and start with cold water.

Ingredients

Makes about 700ml

• 1.5kg (3lb 5oz) beef bones cut to fit the cooker
• 1 tbsp rapeseed oil
• 2 onions halved, skin on for colour
• 2 carrots
• 1 stick celery
• 1 tbsp tomato purée
• 2 litres (3.5 pints) cold water or to 3cm below the rim
• 2 bay leaves
• 6 black peppercorns
• 30g (1oz) butter
• 30g (1oz) plain flour
• 1 tsp balsamic vinegar
• salt and black pepper

Kit

• Roasting tin
• Slow cooker of at least 5 litres
• Fine sieve
• Wide pan

Method

1. Heat the oven to 220C fan (240C conventional, gas 9). Oil the bones and roast for 50 minutes, adding the vegetables and tomato purée for the last 20, until everything is deeply browned. The slow cooker will not brown a thing, so this stage carries the whole flavour.

2. Transfer to the slow cooker. Deglaze the roasting tin on the hob with a mug of water and pour that in, then cover the bones with cold water, stopping about 3cm below the rim.

3. Add the bay and peppercorns, put the lid on and set it to low for 12 hours. Low on most machines holds around 90C, which is the exact temperature a good stock wants and which is fiddly to maintain on a hob for that long.

4. Resist lifting the lid. Every peek drops the temperature significantly and slow cookers are slow to recover, so you lose more time than you gain.

5. In the morning, ladle the stock out through a fine sieve into a bowl rather than tipping the whole heavy pot, which disturbs the sediment and clouds the lot.

6. Chill for a few hours until the fat sets, then lift the cap off. You should have about 1.6 litres of stock which sets to a soft jelly.

7. Pour 1.2 litres into a wide pan and boil down to 800ml over about 20 minutes. Slow cooker stock loses no liquid to evaporation, so this reduction step does more work than usual and is what turns broth into gravy.

8. Make a roux with the butter and flour, cook it 2 minutes to light gold, then whisk in the hot stock and simmer for 5 minutes. Add the balsamic, season and serve.

Tips worth knowing

• Ladle, do not pour. Slow cooker stock settles a fine sediment at the bottom and tipping the pot puts all of it back in suspension.
• Because there is no evaporation, slow cooker stock always comes out weaker than a hob one. Budget for the reduction rather than expecting instant strength.
• Onion skins left on give a noticeably deeper colour and cost nothing. Wash them first.
• Do not fill above 3cm from the rim. Slow cookers bubble more than people expect over twelve hours and a full pot will weep down the sides.

Keeping and reheating

Stock keeps five days in the fridge and six months frozen. Gravy keeps three days chilled. Freeze the stock in an ice cube tray for small jobs.

Questions people ask