Quick demi glace

Makes about 2-3 litres

Big kitchens make this jus, as it's sometimes called, in massive quantities and in vessels similar to the expensive Swiss one we have at The Ivy. It's then a base for sauces, gravies, or for braising meat, such as the oxtail below. For a professional gravy or jus at home, you can easily make more manageable quantities in a domestic pressure cooker. It's the kind of job that makes a pressure cooker earn its keep. If you don't have one it takes more than twice as long in a normal stock pot.

Big kitchens make this jus, as it's sometimes called, in massive quantities and in vessels similar to the expensive Swiss one we have at The Ivy. It's then a base for sauces, gravies, or for braising meat, such as the oxtail below. For a professional gravy or jus at home, you can easily make more manageable quantities in a domestic pressure cooker. It's the kind of job that makes a pressure cooker earn its keep. If you don't have one it takes more than twice as long in a normal stock pot.

1kg chicken or beef bones, cut into small pieces
1 large onion, peeled and roughly chopped
2 large carrots, peeled and roughly chopped
2 sticks of celery, roughly chopped
1 small leek, roughly chopped and washed
1/2 tbsp tomato purée
2 tbsp flour
2-3 litres beef stock or 3 stock cubes, dissolved in that amount of hot water, depending on the size of your pressure cooker
10 black peppercorns
1 bay leaf
A sprig of thyme

Pre-heat the oven to 220º/Gas mark 7. Mix the bones with the vegetables and roast them in a tray in the oven for 30-40 minutes, stirring every so often until nicely coloured. Stir in the tomato purée, dust with the flour then return to the oven for another 15 minutes. Remove and transfer them to the pressure cooker pan. Add about 1/2 litre of the stock to the roasting tray and stir on a low heat for about 5 minutes to remove any residue from the bottom of the tray.

Add that stock to the pressure cooker on a low heat and stir well then gradually add the rest of the stock and keep stirring to avoid lumps forming. Bring to the boil. Add the thyme, bay leaf and peppercorns. Put the lid on your pressure cooker, close and secure it and cook on the lowest heat for 1 hour.

Release the pressure until the steam stops and remove the lid. Strain the sauce through a fine-meshed sieve, skim off any fat and leave to cool. If you want your sauce a little thicker you can simmer it for longer to reduce, or store it and if necessary thicken it later when you're ready to use it.

Freeze in containers in useable amounts or in ice cube trays for small individual portions. You can then put the cubes into a freezer bag once they are frozen.

If you don't have a pressure cooker follow the recipe but allow up to 3 hours simmering in a pan, and top it up with water if necessary.