Boil, steam or microwave sweet potato until very soft. Mash until smooth.
In a mixing bowl, combine mashed sweet potato, spelt flour, chili powder, ground cumin, oil and salt. Mix well, add water a little at a time to make a soft, pliable dough. I added about ⅔~¾ cup of water.
Cover and set the dough aside for at least 15 minutes.
Divide the dough into 8~10 equal pieces. On a well floured surface, roll each piece into 5~6" round roti.
Heat a griddle or tawa on medium-high heat. Cook each roti until golden brown spots form on both sides. Brush with more oil or ghee, if desired. Serve with a curry or pickle or yogurt.