Add yeast + warm water + sugar to the mixing bowl, mix well and keep aside for 10 minutes or until the yeast froths. Add salt + egg + mashed potato and mix well. To this add 1 cup whole wheat flour and 1 cup all purpose flour (reserving the remaining all purpose flour and using as needed).

Knead the dough with your hand, bread machine or stand mixer fitted with dough attachment until you form a soft and non-sticky dough. If kneading with hand use a wooden spoon to mix the initial mixture and when it gets difficult to knead transfer to a floured work surface and work for additional 6 to 10 minutes. Cover with a cloth and keep this in a warm place to rise for 1-2 hours or till the dough is almost double in size.

To shape into a rosetta: After the 1st rise deflate the dough and divide it into 6 equal parts. Roll each piece into a rope about 12-14 inches long. Tie a knot. Tuck one side below the roll. Bring other aside above the roll and tuck in the middle (check images). Place this on a parchment paper or on a lightly greased sheet, cover with a cloth or greased plastic wrap and let it rise for another 20 - 30 minutes or until almost doubled.

Preheat the oven to 375 degrees Fahrenheit or 190 degrees Celsius. Brush the egg wash evenly on the rolls and on the sides. Sprinkle sesame seeds. Bake for 17-19 minutes or until the top is golden brown. Let it cool in the pan for 5 minutes and then transfer onto a wire rack.