Boil salted water and lard in a rather narrow pot. Add the heath flour in one go and shape it a bit with a wooden spoon, forming a large lump. Carefully pour a little cooking water over this.
Cover and let swell or simmer gently over low heat for about 20 minutes. Carefully drain the cooking water with the help of a lid and collect it. Break up the rather dry chunk of sterz (preferably with a two-pronged meat or sterz fork).
Slowly add cooking water in small amounts, a little at a time, loosening the rather floury mixture with a fork to form uniform lumps. (If little water is added, only small lumps will remain; adding more cooking water will make the lumps of sterz larger, but also moister or soggy).
Heat a little lard, fry the bacon or grammels in it until crispy and then use it to lard or roast through the sterz.