Peel the potatoes, wash and cut into quarters. Put them in a bowl with salt and 1/2 cup (100 ml) of water, cover and hold over 8 minutes at 600 W, and the medium is stirred well. Pour the liquid potatoes and let stand 2 minutes. Pour a milk and the butter in a bowl, capped and held for 1 1/2 minutes at 600 Deut. The mixture was added to the potatoes and the whole was mixed by using a mixer.