Onion gravy is a taste treat and not just for vegetarians. I caramelise the onions in the slow cooker a few days before. It’s amazing to slice six onions with a mandoline, leave them for 12 hours and come back to divine flavour bombs. I’ve included instructions on caramelising as you make the gravy but I highly recommend the slow cooked approach. Will include a recipe in the future.

This gravy improves with a couple of days in the fridge, so make ahead for taste as well as convenience.

Ingredients

• 50 g butter ( 3–4 tbsp olive oil)
• 600 g onions (about 5 medium), very thinly sliced (use a mandoline if possible)
• 1 tsp sugar (helps caramelisation)
• ½ tsp salt (for the onions)
• 2 tbsp plain flour (or gluten-free flour)
• 500 ml strong good quality vegetable stock (hot)
• 50 ml red wine or brandy (optional but highly recommended – replace with more stock if you prefer alcohol-free)
• 1 tbsp balsamic vinegar or Worcestershire sauce
•  1 tsp Marmite or Vegemite (optional, but gives that umami “roast dinner” flavour)
• 1 sprig fresh thyme or ½ tsp dried thyme
• Freshly ground black pepper

Instructions

1. Caramelise the onions – low and slow. Melt the 50 g butter in a wide, heavy-bottomed pan over medium-low heat. Add the sliced onions, sugar, and ½ tsp salt. Stir well, then cover and cook for 10 minutes to soften. Remove the lid, reduce heat to low, and cook 35–50 minutes, stirring every 5–8 minutes, until the onions are deep golden-brown, jammy, and sweet. Don’t rush – proper caramelisation = proper flavour.
   
2.  Build the gravy. Sprinkle the 2 tbsp flour over the onions and stir for 2 minutes to cook out the raw flour taste. Pour in the red wine or brandy (if using) and let it bubble for 1–2 minutes until the alcohol is burned off. Gradually add the hot stock while stirring constantly to avoid lumps. Add balsamic/Worcestershire, Marmite, thyme, and a good grind of black pepper.
   
3. Simmer & finish. Bring to a gentle simmer and cook 10–15 minutes, stirring occasionally, until thickened to your liking. Taste and adjust seasoning; often needs more pepper and sometimes a touch more balsamic. For silky-smooth restaurant-style gravy, strain through a fine sieve, push the onions through with a spoon to keep maximum flavour or blend with a stick blender.
   
4. Allow to cool to room temperature. Refrigerate up to 4 days or freeze up to 3 months. Reheat gently with a splash of water or stock.

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Tags: make ahead onion gravyonion gravythanksgiving gravyvegetarian