Cut the cauliflower into small florets, wash and cook in salted water until firm to the bite. Set aside 1 - 2 cups of the cauliflower cooking water, depending on how much sauce is required.
Heat a large piece of margarine in a saucepan and sweat the flour in it. Then add the cauliflower water while stirring. Then add enough milk until a creamy, not too firm sauce has formed. Bring to the boil and cook for a few minutes, stirring constantly, until the flour taste has disappeared. Season with salt and you`re done.
The sauce is generously poured onto the cauliflower when serving. We always make a lot of sauce, because it always tastes great with the other side dishes, e.g., roast pork or simply bratwurst.