Preparation: Have water in steamer boiling. Dip tomatoes to loosen skins; remove skins; slice in half. Wash and trim bok choy stalks. Use slender end of stalk only (use leaves and thick stalk in other dish). Drain baby corn and straw mushrooms. Steaming: First steam baby corn and straw mushrooms for 5 minutes. Place tomatoes and bok choy on separate plate; sprinkle with salt; steam for 3 minutes; drain. Arrange vegetables on warm round serving platter in flower pattern. Sauce: To render chicken fat, place pieces in small saucepan with a few drops of oil to prevent sticking. Cook on medium heat for 20 minutes or so, until chicken oil separates from solids. Drain oil, reserve. Alternatively, make aromatic oil by steeping several peeled garlic cloves in hot cooking oil (after removing it from heat). In small saucepan, heat chicken stock, peanut oil and sugar. When it starts to boil, dribble in enough cornstarch paste to give a light body. Keep warm until ready to use. When vegetables are being steamed, reheat sauce with chicken oil. Pour sauce over vegetables. Serve.