I usually use the no wash method of cleaning up but sometimes I end up with a frying pan or dishes to wash. I never use soap because it takes a lot of water to rinse the soap off. Instead I use baking soda.
One time I ran out of baking soda for awhile so I used wood ash instead–it worked. To make soap you need grease and lye. Lye is made from wood ash. So, mix the grease from the pan with wood ash and you have essentially made soap.
Baking soda works under the same principal but it is safer on your skin. Wood ash in water releases lye so you don’t want it getting in your eyes or sitting on your skin.