The whole process should generally take only a few minutes, less if you have no hard vegetables. Boiling Most vegetables other than roots and tubers only need a few seconds of boiling time. When done properly, boiling can bring out the beautiful color of a vegetable in less time than steaming. And, when done briefly, the nutritive properties of the vegetable are still retained. Boiling does soften the vegetables, but the point is not to kill them.
Many Japanese dishes require boiling of vegetables in water before further handling.
This is done very quickly and sets the color of the vegetable. Remember to have the water boiling before placing the vegetable in it. Leafy vegetables such as spinach usually only need about 15 seconds. Remove quickly and submerge in ice water to set the color. 30 if you like them soft.