Roux: Add the oil to a saucepan over a low heat. Once the oil has warmed (but before it starts to sizzle!), add the flout and stir thoroughly to make a paste.

Béchamel: pour in the liquid (milk and beer, does not matter what order, or mix together if you like). Do this very gradually, a little at a time - and between each addition, stir the liquid thoroughly into the roux. It's vital to take this part slowly and stir thoroughly, to make sure the sauce isn't lumpy. As the paste becomes more sauce-like you can add a bit more liquid at each pour, until all the liquid has been stirred into the sauce. Whisk, to make sure the béchamel is nice and smooth.

Add the nutritional yeast, garlic, mustard, smoke and plenty of Worcestershire sauce and stir thoroughly. Whisk again.

Now take your sliced bread, and toast one side under the grill. Turn the toasted bread over and carefully spoon sauce onto the bread. Sprinkle a little more Worcestershire sauce over the top and put it under the grill until the sauce begins to colour.

Serve immediately, with salad to garnish.