This dish is something you'll find on menus of Shanghainese restaurants. It's a great way to use up leftover plain chicken. Alternatively you can buy half a roast chicken from the supermarket (or cook your own), or get half a salt-baked or soy sauce chicken from the Chinese roast meat shop (don't let the vendor cut it into pieces).
Mung bean sheets (fun pei) are sold fresh or dried; you can use either one for this dish. Neither type needs cooking - you just soak the sheets in boiling water before cutting into wide strips. Fresh ones need to be soaked for only 30 seconds or so, while the dried ones need a longer time.
Strip the chicken meat from the bones, then it shred it into long, thick strands.
Finely mince the garlic. Mix together the sauce ingredients, then taste and adjust the seasonings as necessary. It should be thin enough to lightly coat a spoon. If it's too thick, stir in some warm water.
Julienne the cucumber.
If using dried mung bean sheets, put them into a large bowl and add boiling water to cover them. Soak the sheets until soft and translucent, then drain, rinse with cold water then drain again. If using dried mung bean sheets, soak them in cold water until pliable, then drain. Bring a pot of water to the boil add the sheets and cook for about five seconds or until they are translucent. Drain, rinse with cold water and drain again. With fresh or dried sheets, cut them into strips about 1cm (7/16in) wide, then separate them into individual noodles.
Spread the noodles over a plate and add a layer of julienned cucumber before topping with the chicken.
Spoon the sauce over the chicken, add sprigs of fresh coriander then sprinkle with sesame seeds before serving.