To finish cooking the greens, heat the oil in a pan set over a medium-high heat. Fry the garlic, chilli and ginger for 30 seconds, until fragrant. Add the lime juice and let it bubble for a minute, then add the drained broccoli along with the soy sauce and oyster sauce. Add the bok choy and cook for a further 3 minutes. Add the vinegar and season to taste, then transfer the veg to a platter and keep warm.