1. You can simply use Liquid Castile Soap direct from the bottle as is.
If you like you can scent it with essential oils & thicken it with saline solution
2. Make your own dishwashing liquid.
By diluting the Liquid Castile Soap you will be able to make it last longer, however it will be rather thin & runny. You can thicken it with xanthan gum & add additional soap flakes for more lather. >> get dishwashing liquid recipe
This is most effective when it's lathered onto a sponge with warm/hot water. Great for when your washing a few items by hand. If you are filling up a sink you are better of using the Dish Powder or Soap Bar.