2green onions, white part only, thinly sliced diagonally, green part reserved
125 ml (½ cup)Shaoxing wine
2 tbsplight soy sauce, or to taste
For shiitake broth, combine ingredients in a wok. Bring to the boil over medium heat, reduce heat to low and simmer to infuse (5 minutes).
Line a steamer basket (large enough to sit snugly within wok) with baking paper. Place tofu and gai choy in basket, season to taste with Sichuan pepper, cover and place basket over boiling broth. Cook until tofu is heated through and gai choy is tender (5-10 minutes).
Thinly slice reserved onion tops diagonally. Divide tofu, gai choy and mushrooms among bowls, ladle over broth, scatter with onions, and serve with steamed rice.
Note Gai choy, also known as mustard greens, is available from Asian and select grocers. If unavailable, substitute bok choy or gai lan.