It depends on what you're making with the cashews, but if you're blending them up into a sour cream, you can use raw sunflower seed kernels or silken tofu instead. For a mayonnaise, silken tofu works really well. If you're using the cashews to thicken a dessert, silken tofu works well there also as in this pumpkin pie recipe. If you're using the cashews whole, as a nut, a good substitute would be walnuts, pecans, sunflower seed kernels, pistachios or almonds.