You do not need water to knead the dough as the water content in sweet corn and onion is enough. If you need just knead well for 5-10 mins check and add water little by little.
Rest for 1/2 an hour. Take a small ball sized dough and flatten as chapati.
Make thin as possible.
Cook in tawa. Apply oil on both sides. Cook in medium flame
Sweet corn Paratha is ready to serve with onion raita.