In a shallow glass baking dish, combine the tea, Chinese five spice, cinnamon stick, and soy sauce. Pour boiling water over ingredients, and let steep for 5 minutes. Discard tea bags and allow to cool slightly. Add cod, cover, and refrigerate, 1 to 2 hours, turning once. Remove fish from marinade and strain marinade through a cheese cloth to remove grainy solids and cinnamon stick.

Heat oil over medium heat in a poaching pan with a lid. Add shallots, sprinkle with sugar and cook until soft and brown. Turn heat up to medium high, add cod and sear one minute on top and one minute on bottom. Pour in marinade and bring to a boil. Reduce heat to low and cover. Cook for 5 minutes or until fish is opaque and almost falling apart. Uncover, remove cod carefully with slotted spatula and turn heat to high. Stir in dissolved cornstarch. Reduce sauce by two thirds, about 10 minutes, until thick. Keep fish warm in the oven or in a warming drawer.

While sauce is reducing, steam baby bok choy in a vegetable steamer over boiling water for about 4 minutes, until bright green and tender when pierced with a fork. Plate the fish, pour sauce around it or over it and decorate the plate with baby bok choy. Serve immediately.