For 1 cup vada, add 2 teaspoons rice flour, 2 teaspoons corn flour, 1/2 teaspoon chilli powder, 1/2 teaspoon salt or salt to taste, 1/2 teaspoon coriander seeds powder and knead. Add a pinch of soda. Other vegetables like gratted carrot could be added. There is no need to add water since upma is already soft. Add 1 or 2 teaspoon water if the batter is too hard. Apply water to your palms to pprevent the batter from sticking. Let it sit for 10 minutes. Wet your hands, take a small amount of dough, press it and put a hole in the middle. Heat oil sufficient for deep fry in a pan. Add some batter and test for heat. Prepare vadas one by one and add them to the oil. Wet your hands, take a small amount of dough, press it and put a hole in the middle. Cook them on medium flame. Flip after they turn light brown. After the other side also turns brown, take the out from the oil and serve hot.