agree with the above answers, but note that the CONCEPT of "filter", even if that word is spelled out, won't be obvious to many users (confirm this via User Research). My 85 year old mother, for example, never uses a filter in the kitchen (food-cooking context) and would never guess that's where she'd tell the computer about her "dietary restrictions" (hint, hint, that might be a better label). To her and others like her, a filter is something in the basement on the furnace, or the drinking-water contraption in the fridge door, or maybe she'd think it's a "screen" - the colander for washing vegetables or draining pasta, etc.
Lesson: avoid abstract general terms (especially technical computer terms) when a domain-specific word is more commonly understood by people familiar with that context. Thus they can understand the term without mapping it to some more abstract term. In this context, restaurant dining, use restaurant/dining context words like "special diets" or "special menu", or "dietary restrictions". (the submenu that appears containing the "filter terms" can further explain, for example "only show me entrees compatible with this diet:")
Note that by going through this analysis, a more natural mechanism may be better (than "filtering" a single giant list of entrees); instead, several specialized-diet mini-menus can be available. I'll bet that's what many restaurants do with their physical-world paper menus.
Thus right at the top of the navigation, offer those alternative menus, or, if, like many paper menus, items are annotated with icons to classify them as "vegan", "celiac", "kosher", etc, whereever your "key" exists to explain those icons (on paper menus, typically at the bottom of each page or the first page), include navigation choices to go to Special Menus containing only such items.