Here's the thing--and I'm not trying to be glib here. We really don't know.

Cookbooks really weren't a thing with either culture. We can look at midden heaps to find the remains (and seeds) of various food animals and plants, but that doesn't tell us much on how they were prepared or what they tasted like.

Now, that said, the main foodstuffs seem to be largely the same--locally-grown vegetables with the occasional pork and lots of bread and porridge--but the actual preparation of such could be very, very different.

To use a wholly modern example, let's look at American chili. That can be anything from minced sirloin cooked in a chili-based sauce to a pile of beans and meat heaped on rice or noodles to a green stew of pork and potatoes.

We know what grew there, we know what they ate. We don't know exactly how they prepared it.