Mix the dry ingredients together. Add the mashed potato and combine. Add the rest of the ingredients. Combine loosely in the bowl. Empty the dough onto a floured surface and knead for about 10 minutes, until smooth and silky.
Place in an oiled bowl and cover loosely with a tea towel. Allow to rise to double its size (about 1 1/2 - 2 hours). Again, turn the dough out onto a lightly floured surface. Press gently and knead for 2 minutes. The dough will still be very sticky - this is probably because the mashed potatoes make it so. I don''t think adding flour helps - and it certainly makes the loaf very dense, so try not to add too much, just enough to keep your fingers and the counter from the sticking to the dough.
Shape the dough (I made a free form loaf) on the baking tray or in a loaf pan. Cover with the tea towel and allow to proof for 45 minutes. Preheat the oven to 230 deg C.
Bake for 35-40 mts. Remove and allow to cool on a wire rack for 5 minutes. Bread is usually still cooking when taken out of the oven, so its not a great idea to slice into it immediately. If you do, you will see that its "gummy" and looks undercooked. Cooling for 5 minutes or longer is a good idea for most breads.