you need to let the turtle live in some clean water for a bit of time before you cook it up, i would wait at least 48 hours, but longer is better. Just put him in a large container (that it cant get out of) with tap water and change the water daily. My uncle regularly eats smaller snapping turtles, and this part is crucial.
thanks guys, i dont think ill be having turtle soup for a while because my mom thinks the idea is gross and shes the one that picks me up from the pond so she proably wont let me put a snapper in her car