Peel the potatoes, cut into cubes, boiled and mashed. The water in which they were boiled, be retained. Cool 1/3 cup and it was dissolved yeast. To mash the potatoes add the flour, yeast, sugar and the oil and pour 1 1/2 cups potato water. Mix a little before he assumed the flour add mustard seeds and grated cheese. Once good knead, allowed to rest for 40-50 minutes in a square form cakes, and then baked for 40 minutes at 180 C.