Stir together the stock and sherry. Set aside.
Heat a 14-inch flat-bottomed wok or large iron skillet over very high heat until a drop of water evaporates within a second or two when added to the pan.
Add the oil to the skillet and heat until shimmering.
Cook the ham until the fat is rendered, about 30 seconds
Throw in the garlic and ginger and cook just for 10 seconds.
Start stirring and add the onion stirring continuously, for 1 minute.
If you are using a wok move any ingredients up the sides if they start to brown too much. Don't burn anything.' Add the turnips and stir-fry for another minute or two, then season with salt and pepper.
Pour in the stock mixture and toss together quickly with the vegetables.
Mix in the greens and cook, stirring, until the vegetables are crisp and/or tender—3 to 5 minutes.
Taste and adjust for seasoning with salt and pepper.
Drizzle with honey, if you choose, and serve immediately