Soaking cashews before roasting is not mandatory, but some people prefer soaking cashews before roasting to improve their texture and make them easier to digest. Soaking cashews can soften the nuts and remove some enzymes and phytic acid that can interfere with their digestion. However, soaking cashews can also reduce their natural flavor and nutrients, so it's vital to balance the benefits of soaked cashews with the desired outcome of roasted cashews. If you prefer a crunchier texture and a strong flavor, you may skip the soaking step, but if you want a tender and easier-to-digest nut, soaking may be a good option.