Slow Cooker Onion Gravy

The slow cooker will not brown onions on its own, whatever the internet says. What it will do is break a kilo of them down into something soft, sweet and deeply concentrated with no stirring at all. Give them fifteen minutes in a hot pan at the end and you get the colour too. It is a lot of hands off time for very little effort, and it makes enough for two or three meals.

Ingredients

Makes about 1 litre, enough for eight plates

• 1kg (2lb 4oz) brown onions halved and sliced 4mm thick
• 50g (2oz) butter cut into cubes
• 1 tsp fine salt
• 1 tsp dark brown soft sugar
• 1 litre (1¾ pints) hot beef stock
• 2 tsp Worcestershire sauce
• 3 tbsp cornflour slaked in 5 tbsp cold water
• black pepper

Kit

• Slow cooker
• Large frying pan
• Small bowl

Method

1. Pile the onions into the slow cooker, dot the butter over the top and scatter over the salt. Do not add any liquid. The onions will release plenty of their own within the first hour.

2. Put the lid on and cook on low for 6 hours. Stir once at the halfway point if you happen to be passing, but it is not essential. At the end they will be pale gold, completely collapsed and sitting in a pool of sweet oniony liquid.

3. Tip the whole lot, liquid included, into a large frying pan over a medium high heat. This is the step people skip and it is the one that matters, because the slow cooker gives you softness but never colour.

4. Fry for 15 to 20 minutes, stirring often, until all that liquid has boiled off and the onions start to fry rather than simmer. Once the pan goes dry they will brown fast, so from that point stir constantly for 5 minutes until they are a rich brown.

5. Add the sugar, let it melt, then pour in the hot stock and the Worcestershire sauce. Scrape every brown patch off the base of the pan and bring to a simmer.

6. Simmer for 10 minutes, then stir the cornflour paste smooth and pour it in slowly while stirring. It thickens almost immediately. Simmer for 2 more minutes, then grind in plenty of black pepper and season to taste.

Tips worth knowing

• Do not add stock to the slow cooker at the start. You want the onions to concentrate, not to boil in liquid, and adding stock early gives you thin onion soup.
• This freezes better than almost any other gravy. Portion it into a muffin tray, freeze, then bag the pucks and drop two or three straight into a pan whenever you need gravy.
• If your slow cooker runs hot and the onions are catching at the edges, that is fine, just stir those darker bits through.
• Six hours on low is the sweet spot. Eight is fine too. Four is not enough and you will taste the difference.

Keeping and reheating

Fridge for 5 days, freezer for 4 months. Reheat from frozen straight into a pan over a low heat with a splash of water, stirring as it melts.

Questions people ask