I think that because of how slow the cooking process is, even though the exterior is solid black due to smoking, it's an incredibly thin layer of solid black. So it's something like a half millimeter as opposed to like an eighth inch of carbon you'd get from burning a steak.
You can kinda see it in this photo: https://www.alamy.com/bavarian-specialty-schwarzgeraeuchertes-smoked-pork-belly-sliced-hengersberg-bavaria-germany-europe-image280002380.html
Very pink all the way up to a razor thin layer of black.
I think that because of how slow the cooking process is, even though the exterior is solid black due to smoking, it's an incredibly thin layer of solid black. So it's something like a half millimeter as opposed to like an eighth inch of carbon you'd get from burning a steak.
You can kinda see it in this photo: https://www.alamy.com/bavarian-specialty-schwarzgeraeuchertes-smoked-pork-belly-sliced-hengersberg-bavaria-germany-europe-image280002380.html
Very pink all the way up to a razor thin layer of black.