The menu.
We ensured that we ordered different dishes for each to increase the chance of satisfaction. For the starters, I ordered "Charcuterie" at random, while Jen ordered "Salade au Roquefort", knowing that "Roquefort" was some kind of cheese. For the mains, I ordered "Pave de Bouef", knowing that it was beef, and Jen ordered "Pave de Saunoiy" at random. The beef had a "Roquefort" sauce, so we knew it was some kind of cheese sauce. I raised the objection that perhaps this meant blue cheese (which I don't like much), but Jen smugly pointed out that they'd just say gorgonzola or the like in that case. I theorised that Jen's dish ("Saunoiy") was probably salmon, but Jen smugly retorted that "poisson" was the French word for fish, so it probably wasn't.