Boil the potatoes and cut them into small cubes. Do not over-boil them else they will turn too mushy. Dice the onions into cubes.
In a large bowl, mix together all the ingredients listed under "to marinate". Let the marinated mixture sit for 30 minutes.

Heat 1-2 tsp of oil in a pan, once hot add the cumin seeds.
Once the cumin seeds crackle, add the marinated mixture mashed potatoes then add 1 tbsp tomato ketchup. Mix everything together.Cook for 7-8 minutes on medium-low flame. Remove the pan from heat once done.

Take a tortilla and apply some green coriander chutney in the middle, place the potato mixture on top and garnish it with sliced onions, cheese, tomato ketchup and some chaat masala.
Fold the tortilla to form a wrap.

Heat some oil in a grill pan and cook the wrap for 1-2 minutes from both sides or till you see few light golden brown spots on surface.

Serve immediately with any sauce or dip of your choice.