Melt 2 tablespoons of Butter in a saucepan over a medium-low heat. Add 2 Onions (thinly sliced) and stir until coated.
Add ½ teaspoon of Sugar and cook gently for 15-20 minutes, stirring occasionally, until the onions are soft and golden.Cook for longer if you prefer a deeper caramelised flavour.
Reduce the heat and stir in 2 tablespoons of Plain flour. Cook for 1 minute, stirring so the flour doesn't burn.
Gradually stir in 100 ml of Red wine, if using, followed by 300 ml of Beef stock, adding a little at a time to prevent lumps. Stir in 2 tablespoons of Worcestershire sauce and ½ teaspoon of Dried thyme.
Bring to a gentle simmer and cook for 3–5 minutes, stirring occasionally, until the gravy thickens enough to coat the back of a spoon.
Taste and adjust the seasoning. Add a splash of water or extra stock if you prefer a thinner gravy.
Notes
Don't rush the onions. Cooking them gently gives the gravy its sweetness and flavour. If you have more time, leave them for an extra 10 minutes to develop a deeper golden colour.
Add the stock gradually. This helps prevent the flour from forming lumps and gives you a smoother gravy.
Adjust the consistency. If the gravy becomes too thick, stir in extra stock or water a tablespoon at a time. Remember it will thicken slightly as it cools.
Taste before adding salt. Stock and Worcestershire sauce already contain salt, so you might not need any extra.
Make it smooth. We like the texture of sliced onions, but you can finely dice them or blend the finished gravy with a hand blender.
Add extra flavour. A teaspoon of Dijon mustard adds a lovely tang, while a splash of single cream makes it a little richer.
Give it a festive twist. Stir in a teaspoon of cranberry sauce for a little sweetness, particularly when serving it with Christmas dinner.
Use the roasting juices. If you're making a roast, stir in a little of the meat juices for extra flavour, tasting before adding any more salt.