Raw ugthanki meat can be obtained by killing an ugthanki. It can be cooked at level 1 Cooking, granting 40 Cooking experience if successful. After successfully cooking it, it will be ugthanki meat, burning it will result in burnt meat. The raw ugthanki meat cannot be made into sinew, and cannot be cooked twice to create burnt meat.
For an exhaustive list of all known sources for this item, see here
- Even though it does not have a cooking level requirement, it is still possible to burn the meat, even at high cooking level, such as 70.