We have an old fashioned food processor (meat grinder) on board. They're easy to find in thrift stores, and generally cost anywhere from 10-15$. It has quickly become one of our favorite galley tools.
We first decided to get one to process peanuts into peanut butter, and to process wheat berries into a mush to bake bread.
We have since found that it works well to grind soybeans to make soy milk. They are easy to take apart and clean, but the metal discs should be coated with vegetable oil after every use, otherwise they will rust.
We also like to use a simple potato masher to make hummus, cooked beans are easy to squish by hand.