上湯豆苗 (shàng tāng dòu miáo) is a basically very simple dish of mangetout leaves moistened with a rich stock, though it can be jazzed up with garnishes such as century egg or peeled prawns (as in the version pictured above, which I ate at Red & Hot in London). English translations I've seen include "pea shoots in rich broth" or simply "pea shoots in soup" [see footnote].
Wikipedia tells me that 上湯 is a "dark tan broth made from Jinhua ham and chicken", while the Red Cook blog states that it's made by adding more fresh meat to an already-made clear stock, and simmering further. The eGullet forums have a nice discussion of Chinese stocks, including a recipe for 上湯. As that recipe points out, it's worth blanching the meat before you begin (I've discussed this before — see the comments too).
The eGullet recipe also mentions that you should choose an old chicken rather than a young one, for better flavour, and simmer the stock for 6-8 hours. I can thoroughly endorse this suggestion. I bought a "fresh Scottish hen" from the Chinese butcher (he described it as 老雞/lǎo jī/"old chicken") and let the stock simmer at a very low temperature for 8 hours, and it was the chickeniest chicken stock I've ever made. The fact that the neck and feet were also included probably didn't hurt either. The meat itself won't really be worth eating after such a long time — you can eat it if you like (I nibbled a few bits), but the flavour will mostly be gone.
Note that the low temperature is important — if you let the stock boil while you're making it, it will be a creamy/cloudy colour rather than nice and clear. This isn't something specific to Chinese cuisine; in the River Cottage Meat Book, Hugh Fearnley-Whittingstall insists that a stock should never go above "a very gentle simmer, whereby a few bubbles just tremble the surface every few seconds or so".
A word on the dried scallops — these are a very expensive ingredient, and not all that easy to get hold of in the UK. I'm not entirely sure what the situation is regarding these — they're certainly not illegal to sell, since I found them at See Woo in London's Chinatown (at £40 for a 200g gift package of around 25 scallops, and no, that isn't a typo) — but as Helen Yuet Ling Pang points out, they're not often available in the shops. One suggestion given in the eGullet thread linked above is to try substituting them with a bit of dried squid — or you could just leave them out.
Jinhua ham is also not very easy to find — I asked in three Chinatown supermarkets, and none of them had any. Serrano ham or some other dried non-smoked ham might work as a substitute.
Anyway, my stock turned out well, but I shot myself in the foot when it came to making the dish. I couldn't find any pea shoots, so I thought I'd try spinach instead, but accidentally picked up a bag of something that turned out to be labelled "kai choi" — mustard greens (芥菜/jiè cài). Their flavour totally overwhelmed the flavour of the stock, which was a bit disappointing given how long it had taken to make! I'd say this dish is definitely best made with milder-flavoured greens.
The method I used was fairly simple (cribbed from a blend of two recipes, one from Noob Cook and the other from Portion Perfect) — heat oil in a wok over medium heat, add some chopped garlic and stir it around briefly, add the washed leaves and continue to stirfry until they've wilted, pour in some 上湯, season with a drizzle of Shaoxing wine and a small pinch of salt, let it get hot, and serve.