I don't mean to dog-pile on this topic, much respect to everyone involved. I was just reading up on this and had my eyes twitch a few times.
It would seem like the topic of descriptions of 'racial features' is still on the table. If not, my apologies. I'll toss my tuppence at it. This being from a Canuckistanian who exists in the frigid wastes of Political Correctness, as well as someone who lived in Nihon for a few years teaching English. Also, just an idea that might not have been touched upon, yet, which could help with writing for anyone who might find it useful...
JoeBB, you mentioned describing a given character in your story. I think that's Kaze (Wind)? That she has Asian-type features and you want to describe how she looks. A great way to do this is to put yourself in her shoes as a character. I'm going to have to assume here, that you're Caucasian and from... I'm guessing, the U.K.? Imagine yourself as Kaze. Imagine growing up in a household that is predominantly Japanese. How would she describe herself different from say... Her sister? Her parents? Or a cultural icon from 'back home' that she grew up with? Imagine yourself not being able to use any kind of racial descriptor.
Then describe who she is and how she looks. Does she have full lips or thin? Are her cheekbones high or sullen? Does she have the more almond shaped eyes of people from Eastern or Northern Japan (Hokkaido, Tohoku, Kanto)? Or does she have more puffy eyes and a darker complexion like the people from the South or the islands (Okinawa, Kyushu, Shikoku)? Is she of mixed heritage? Did she ever get called "haafu" by friends or cousins growing up? Does part of that define who she is or does she try and let it go? Does she dye her hair or does she enjoy the dark and straight hair she got from her mother? Stuff like that.
If you're not going for the high-development and just want to keep things short and pithy. Just go with 'Asian' or better yet, her actual heritage. If she's Japanese, say so. If she's Vietnamese, Cantonese, Mandarin, Taiwanese, Korean, or anything else, just say so.
As people have already mentioned, yes, 'Asian' encapsulates a lot more than just people who might be 'East Asian' or referred to in old British academic circles (usually pre-Enlightenment history and in comparative studies) as 'Oriental' when contrasted to the European 'Occidental.' If you just want to mention it and move on, go with it. If you want to be more accommodating to readers or explore that character's background, then mention where she is from, or where her heritage is from, and move on.
Whatever you do, please don't use the term 'mongoloid.' I don't know if you're from the U.K., but I have a lot of family from there (consider it home, once Canada starts burning here soon). I'm sure you understand, that particular term has some very disparaging connotations. Not just for people from Mongolia or who have North-east Asian features, as well as First Nations people here in North America. But, it's also a negative term used for people with developmental disabilities/syndromes.
To go further devil's advocate on the broad-range idea, 'Asian'... Think of this... A lot of people of Latino/Latina descent are very fiercely protective of their cultural identity. I've had a few friends growing up, some from Europe, and some from Mexico/The U.S., that are very protective of their Latin/x culture. Now... Try telling a Latino/Latina person that they're "European" or "Caucasian." I've had a few friends stare at me with daggers when I tried to take the piss like that.
Sometimes it's just best to go with a person's culture as it is, than trying to skirt around the issue. "I'm Japanese-American. My father was stationed in Guam. My mother is from Osaka. They moved to Portland and... Well, here I am. Does it matter too much? It shouldn't. I'm a super-hero!"