Cài Bāozi (菜包子) is the vegetable-filled member of the steamed bun family: a soft, leavened wheat dough wrapped and pleated around a cooked vegetable filling, then steamed until the skin is glossy and the inside is hot through. The angle is the filling doing all the work without any meat to carry it. A cài bāozi succeeds or fails on whether the vegetables are seasoned and bound well enough to taste like a deliberate dish rather than damp greens in bread, and on whether the dough is steamed to the right tenderness.
The build follows the standard baozi method with a vegetarian core. The dough is a yeasted wheat dough, kneaded, proofed, and rolled into rounds thicker at the center than the edge so the pleated top does not turn gummy. The filling is the variable: commonly chopped Chinese cabbage or other leafy greens wrung dry, often with vermicelli noodles, pressed tofu, wood ear or shiitake mushrooms, and sometimes scrambled egg for body, seasoned with soy, sesame oil, ginger, and white pepper. The filling is portioned onto each round, the edges gathered and pleated into the classic twisted knot, and the buns proofed briefly before steaming over high heat. Good execution shows in three things at once: a skin that is soft and slightly springy without being wet or collapsed, a filling that holds together when bitten rather than sliding out, and seasoning strong enough that the vegetables read clearly through the plain dough. Sloppy versions are easy to spot. Greens that were not squeezed out leak water into the dough and leave a soggy base. Underseasoned filling tastes washed out, since steamed cabbage is mild and the bread is neutral, so there is nothing to lean on. Oversteaming or a slack dough produces a wrinkled, deflated bun, and a too-thin wrapper splits and dumps its contents.
It shifts mostly by which vegetables and binders go in. A cabbage-and-vermicelli version reads light and clean; one heavy with mushrooms and pressed tofu eats almost as substantial as a meat bun. Adding scrambled egg or a little fried gluten gives richness against the greens, while chives or garlic chives push it sharper and more aromatic. The same dough wrapped around pork is a different bun entirely, and the open-topped steamed forms and the pan-fried shēngjiānbāo are related preparations that work on different principles and deserve their own articles rather than being grouped in here. As a breakfast item it is usually eaten alongside congee or soy milk, the plain warm bun balancing the thinner liquid.