Yes, bok choy can be blanched. To blanch bok choy, bring a saucepan of water to the boil and add the cleaned bok choy. Cook for no more than 2 minutes, then remove and drain the water. The blanched bok choy can be rested on paper towel to drain, then use it as needed. Just take to not overcook it after blanching, it doesn’t need more than a quick last-minute heat in the stir-fry or it’ll lose its vibrancy and texture.