cooked food, cook until well done
飪 centers on food that has been thoroughly cooked: the process of cooking until well done and the resulting cooked food itself.
飪 combines the food radical 飠 with 壬, which likely contributes the sound. The character expresses the idea of cooking food thoroughly.
The food radical 飠 on the left shows this is about eating. The right side 壬 looks like a pot on a stand. Picture food cooking in a pot until it is well done.
For ジン, imagine a chef named Jin who insists on cooking everything until it is perfectly well done: Jin -> ジン, and his food is always thoroughly cooked.