1. Meuniere refers to a sauce and/or a way of preparing food, but not the food itself. It's like saying "Tonight we're having alfredo," when a proper answer would be something like "chicken alfredo" or "spinach alfredo".
2. "Gohan" can mean "meal" or it can mean "cooked rice", which culturally equates to "meal" in Japan because it's traditionally the main ingredient of most meals.
So, it COULD be a pun on "rice dinner meuneire" and "meuneire for dinner"...maybe. Assuming there's any such layer of meaning in there, that's the best I can make of it.
What's for today's dinner?I see...Which meuniere?...Meuniere.It'll be meuniere.Dinner's...Dinner's......meuniere!