For the rolled roast with celery stuffing, clean the celery and cut into very small pieces. Also dice the onion very finely. Heat a little oil in a pot, sauté the celery and onion, cover and steam for about 5 minutes.
Unroll pork belly and rub with salt and roast pork seasoning. Also add a little salt and pepper to celery filling and spread on meat.
Roll up pork belly and tie roll tightly with sausage string. In a roaster, first put the lard and then the pork belly, add about 1/4 liter of water and roast covered for about 90 minutes.
Then remove the lid and roast for another 15 minutes.