The gerund phrase in this sentence is <u><em>washing dishes</em></u> and it is used as a <u><em>predicate nominative</em></u>. The subject in this sentences is job, the verb is a conjugation of to be (is), and the gerund phrase washing dishes is playing the role of the object of the sentence.
Gerund phrases frequently serve as predicate nominatives and do not have to come at the end of the sentence. Another example would be:
Making noodles from scratch is my hobby.
Subject: hobby
Verb: is
Predicate Nominative (object): Making noodles from scratch
