Soak the cashews in filtered water for at least 4 hours or overnight. Drain and rinse.

Peel the bananas and break them into chunks. Place the banana chunks into a sealable plastic bag and freeze completely until you're ready to use. Remove frozen banana chunks from the freezer 10 minutes before you're ready to make the ice cream.

Combine the drained cashews and 1/2 cup of filtered water in a blender and blend on high speed until you have a completely smooth cream. Set aside.

Slice the vanilla bean down the center and scrape the seeds out with a paring knife. Add the seeds to a food processor along with the frozen banana chunks, cashew cream, sea salt, maple syrup, coconut oil, and lemon juice. Flip your processor to the highest setting and blend the mixture until smooth. Taste the mixture for sweetness and add more maple syrup if desired. Fold in the chopped walnuts and cacao nibs. Scrape the ice cream out into a glass or metal container and freeze for at least 4 hours.

To serve, remove the ice cream 5 to 10 minutes before you plan to enjoy so that it's soft enough to scoop.