Mash boiled potatoes nicely and cut Onions, Cucumber and Tomato into small pieces. Keep vegetables and mashed potatoes in different bowls.
Heat oil in the pan and fry some cumin.
Now mix mashed potatoes in it and saute it for a minute on a medium flame.
Add garam masala and salt. Keep it on low flame for half a minute.
Add Naagin Bhoot Hot Sauce and mix it well. Switch it off. Now take out the vegetable bowl and add mayonnaise & chat masala. Mix well.
Take two slices of bread. Spread evenly the mixture of potatoes on one slice. Put the mixture of vegetables and lettuce leaves over the layer of potatoes nicely. And cover it with the other slice of bread.
Apply butter on both sides of sandwich and toast the same.