Complex sentence: Its stem is used as a condiment and has an extremely strong pungency more akin to hot mustard than the capsaicin in a chili pepper, producing vapours that stimulate the nasal passages more than the tongue.
Split into simpler sentences: Its stem is used as a condiment that has an extremely strong pungency similar to hot mustard (not the capsaicin in a chili pepper). It produces vapours that stimulate the nasal passages more than the tongue.