making yoghurt at home, page-2

I can remember that there was often a bucket of milk, with the cream skimmed off, (for real butter), sitting on the floor near our wood stove.
It was probably more like sour cream than yoghurt, excellent on boiled spuds.
Had the consistency of 'jelly' almost.
Does anyone know how this is made exactly?
Mum was Ukranian, but I think got most of her cooking experience in Germany, more so in the German work camps.
That was a topic hardly ever mentioned, let alone discussed.