in vietnam, the citrus fruit that was served as a condiment to all soups and noodles was small (about an inch in diameter), green skinned, and orange on the inside. it has prominant seeds, which i always got in my soup, but which the vietnamese could remove from the halved fruit with a flick of their wrist.
when i took cooking lessons in vietnam, the teacher told me this was a kumquat. it is most definitely not. my research seems to indicate that it is a calimansi (or kalimansi) which is better known as a philipino ingrediant/condiment than a vietnamese one. however, the kalimansi i have found at local philipino markets are not the same - they are smaller, orange when ripe, and (i think) a little more sour.
does anyone know what the proper name of the proper vietnamese citrus is, and where i can find some? i'm doubting they're readily available, because you get a plain old lime with your pho here (and that plain old lime has nothing on the fruit that i got in vietnam). i've never seen them in all my exploration of SGV asian markets, but i'm willing to go much further afield. i'd also be interested in seeds or year old plants, if anyone knows of an exotic citrus nursery in the area.