If the head of an offering is buried in hot ash to singe off the hair, and if that was in the place of the slaughtering in an upright position, the blood flows out (yes, very gory) and after it is removed, the meat can be eaten. Plus, attention to the inner and outer sinews of the animal’s thigh, and the difference between a rabbinic vs. a Torah-level prohibition (the inner one being the gid ha-nasheh). But can the butchers be trusted in what they have to say about the kashrut of the meat, about the removal of the sciatic nerve? In the end, the conclusion is that they are trustworthy. But it’s a complicated process and with more and less taxing elements, which might influence their credibility.