To provide a method for freeze-processing swamp cabbage (Water- convolvulus, Ipomoea rap tans (Linn), belonging to the family, Convolvulaceae as a Chinese vegetable, to provide condiments for cooking the freeze-processed vegetable and to provide a method for cooking the swamp cabbage.

The method for freezing-processing swamp cabbage is characterized by comprising a harvesting/removing step for the swamp cabbage requiring for longer than 40 cm, a washing/draining step, a cutting step to cut to an even length, a scalding step for scalding it in a cooking pan (Chinese frying pan) in which water is boiling, a draining step, a freezing step wherein the obtained vegetable is held on shelves in a freezer at -40$0C for about 1-2 h in such a state that the swamp cabbage is arranged on freezing sheets laid in cooking bats, and a weighting/bagging step for the weighed frozen swamp cabbage of a predetermined weight. Thereby freeze-processed products of the swamp cabbage are obtained.