Heat a little oil in a wok or large frying pan, over a medium heat. Add the sausages and prick them so they don't burst.
When the sausages begin to sizzle, add 1 teaspoon of the mustard and 1 dessertspoon of the honey.
Gently fry the sausages in the honey and mustard mixture until they are lightly browned all over, then add the onions and stir-fry until the onions are tender and just beginning to brown.
Add the stock and the remaining 1 teaspoon mustard and 2 dessertspoons of honey. Increase the heat to medium high and simmer, stirring, until the stock has reduced to a thick, sticky sauce, about 10 minutes. Serve immediately.