I sincerely hope this is relevant:
I am looking for an idiom for a boring but essential part of work, that goes hand in hand with the core interesting parts of it. On the lines of "peas and carrots" but where one looks more important and interesting, yet the other is essential, e.g. (due to lack of imagination on my part) more like "Matar Paneer" (Peas and Cottage cheese, an Indian cottage cheese curry).