In a small bowl, dissolve the yeast with about 125 mls of the warm water. Add the sugar and oil and let it stand for approximately 5 minutes for the yeast to start frothing.
In a larger bowl, add some flour, the mashed potato and the salt. Gradually work in the yeast mixture into the flour and the warm water and mix it all slowly, alternating the flour and water until you form a soft dough.
Cover with gladwrap and allow it to rise to double the size (approximately 1-2 hours).