Perhaps branching off of the survival tree of skills, something about increased success and efficiency with using primitive firestarters (like bow drills, flint, or rock flaking).
In addition to this there could also be an offensive ability (Pyromaniac?) that can allow you to use fire as a combat/raiding tool, but it would have to branch further off the previous firestarter skill.
I can guarentee you almost everyone can cook a piece of meat on a stick over a fire. And oil isnt required especially in a survival situation where you’re not gonna find bottles of olive oil just lyin around.
Pretty much anyone can cook food, but some people would be better at cooking it right.
I don’t think most recipes should be locked behind a skill tree, just that better chefs should have a better results, for example a low level chef might undercook a steak (which would make it damage immunity, or overcook it (which would decrease the amount of hunger and thirst it restores) while an experienced chef would cook food just the right amount.
I’ve lost the ability to edit this post, but here’s an expansion from RedComm that does a wonderful job going in-depth with some of the wildlife and hunting/foraging mechanics:
One thing that I want to point out is that Unturned is kinda meant to be a bit cartoonish and funny, not just a rigid survival game like some crazy games. So, some stuff, like more precision on cutting down a tree, or more woodland foraging, or - wait - the clothes wet idea is awesome, but just a little bit overboard.
Also, I’d love to see some sleeping in Unturned! That could be another bit along with your suggestions @GreatHeroJ. Maybe like a stamina cap, where when you get tired, you cant fully regen your stamina?