While not same flight as yours, but I flew SFO-ICN-SFO in Y a few weeks ago-

The out bound SFO-ICN catering was better than I expected for a 12 hour flight. The first meal had two hot choices, about mid flight they had a sandwich roll along with ice cream, and prior to landing they also had two hot choices.

The return ICN-SFO was a 10 hour flight, first meal had two hot choices, not sure if they had served mid flight snack since I slept till they were serving the one-choice breakfast.

I have to say the outbound meals were all edible and not bad. However on the return that breakfast "McMuffin"'wanna-be was pretty

Its been a while since I've flew UA Y on a transpacific (have been flying NH Y before the mileage accrual devaluation) and you definitely do not get fed as well on UA as NH.