Can be earned through the tutorial.
After killing and skinning a crab, simply create and light a campfire, have the crab meat in your hand and walk over to lit campfire. There will be an option when you have your cursor on the campfire for you to press/hold X to put the meat onto the fire.
Wait a short while until you hear a ding which signifies it is cooked. You may now take the meat off of the fire an eat it.