It's sliced while rock-hard from the cold, curling off the fish in thin frozen ribbons that are meant to melt on your tongue rather than be chewed.
Stroganina is raw fish — typically muksun, nelma, or omul — frozen solid immediately after catching, then shaved into thin curls with a sharp knife and dipped in a mix of salt and pepper. Vendors and fishermen sell it straight off the ice at Siberian and Arctic river markets, no cooking involved.