I love how your reasoning for the inclusion of Bok Choy is because there are Asian restaurants in SF, rather than the fact that it's one of the most popular vegetables in the most populous country on Earth.
Technically if you "search" your emojis for "bok" and then "lettuce" the same emoji appears. My first guess was that bok choy meant "leafy green" but it means "White Vegetable". I actually had this discussion yesterday, otherwise i wouldn't have known bok choy was an emoji at all.