I LOVE THIS KIND OF QUESTION it evokes someone's nostalgia for tumblr posts like "what would the avengers order at starbucks". unsure if it's my personal nostalgia. maybe it is. i think it probably depends on the sort of au, as i imagine in a modern au as an autistic4autistic relationship they have Specific Favorite Restaurants that they frequent. that can probably happen in canon too. but they also are the couple that's like "where do you want to get food?" "i don't really mind, where do you want to get food?" "i asked you first, i don't mind either" "..." "......" "............." stalemate. i think faust buckles first because she always does, and here buckling first means she chooses a restaurant and leno is happy with it because they are. i don't imagine either of them are particularly picky about cuisine (sensory issues aside) and they're both pretty polite even so. but i also imagine they're both accustomed to cooking for themselves, so they might just fix dinners in... or go to nero for food... faust may not like to go out too much in central. but leno traveled a lot and probably (in fact, canonically) knows cool little spots in different countries, so maybe during missions she steals faust away for the evening for a date at some little diner in the south or something... tries to impress faust with her culinary knowledge and faust is just glad leno is being direct about what she wants to eat for once.