It depends on whether you are steaming large steamed dumplings or small steamed dumplings, as well as the heat and stuffing. Generally, a fire is needed. If it's meat, it takes about 20 minutes for the big one and 15 minutes for the small one, depending on how small you are.

If it's frozen jiaozi, it's best to use cold water and put it in after boiling. If the frozen skin is softened by heat, it will be cooked easily, but the frozen stuffing inside will not be cooked so quickly, so the dumpling skin will rot. Fresh and freshly wrapped jiaozi is best steamed with hot water.