I received a bunch of pork fat from my butcher and not exactly sure what the best way to grind it is. Right now it is frozen in about 9x6 slabs. Some slabs still have the rind on others dont. I am planning on using it for venison sausage, my venison is already ground from the butcher. What would be the best way to add the fat to the venison? Do I grind it frozen or partially thawed?