Peel potatoes and cut them into sticks by cutting each potato vertical in 3-4 pieces first and then cutting further into sticks.
Mix sugar and water in a large bowl. Dip the potato sticks in water. Put it in the fridge for 2-3 hours and allow them to soak.
After 2 -3 hours take them out and drain off the water. Lay the potatoes on large tray lined with paper towel. Gently pat them dry.
Heat oil in pan/ kadai or wok (medium high). Dip one potato stick. If you can see bubbles, put the potatoes in batches and cook them for 2-3 minutes.
At this point, they should not be brown. Take them out and let them cool down to room temperature.
Once potatoes come to room temperature heat the oil again at high heat. Again test it by dipping one potato stick. If you see bubbles you are ready to fry.
Fry potatoes in batches till they are golden brown and crisp. Remove them from oil and sprinkle some salt or other seasoning. Serve them hot and crisp with mayonnaise or ketchup.