undersalt

under- +‎ salt

undersalt (third-person singular simple present undersalts, present participle undersalting, simple past and past participle undersalted)

1. (transitive) To season (food) with too little salt.
   • 2007 October 17, Mark Bittman, “Serving Pasta? Forget What You Learned”, in New York Times‎:

     We also learned we overcooked it, undersalted the water and often used the wrong shape.