Heat one tablespoon of oil in a frying pan over medium-high heat.
Add chopped onions and saute until softened.
Mix turmeric and chili powder into frying pan; remove pan from heat.
Stir mashed potatoes and cilantro into frying pan; stir to mix well.
Sprinkle a few drops of water onto each slice of bread. Gently flatten bread.
Spoon 1/4 of potato mixture onto slice of bread. Roll bread into a cylinder.
Seal the edges together by pinching the ends with your fingers; use more water if necessary to keep bread sealed.
Do the same with the remaining 3 slices of bread. Pour three tablespoons of oil into a large frying pan or wok.
Heat oil to a high heat.
Place bread rolls into hot oil and fry until crispy.