Warm the oil in your saucepan over a low heat.

Mix in the flour thoroughly to form a paste (*roux*), removing the pan from the heat.

Add the plant milk a very little at the time, mixing thoroughly at each step. The paste will initially thicken and gradually become more sauce-like. You can start adding more milk as this point.

Use a whisk to finish the sauce.

You now stir in different flavourings to the basic white sauce. For example, add the garlic, mustard and nutritional yeast to make it "cheesy".