Here is the sandwich I invariably make when I face mid-night hunger pangs. Since I usually have boiled potatoes and paneer in my fridge this dish is easy to whisk. Moreover it is a filling, no-cook dish.
If you dont have paneer in your fridge you can add processed cheese although paneer is a healthier option. Mayonnaise adds the much required moisture to the otherwise dry sandwich.
In the sandwich I have also used some vegetable or sabzi leftover from dinner. The leftover vegetable you use could be anything like stir-fried vegetables (containing beans, carrot, capsicum, corn, etc.) or it could be rajma/ chole curry. Please dont use any vegetable prepared with coconut in it. Also, if using rajma/ chole please strain the gravy out and use only the legumes otherwise the sandwich could become soggy.
Given that this is the only cooked ingredient in the dish it can act as a game-changer. In other words, the complete taste rests on the leftover dish you use. If you use stir-fried mixed vegetables it will make your sandwich have delicious crunchy bits here and there. On the other hand, using kidney beans, chick peas out of a North-Indian gravy could make your sandwich have that delicious fiery taste that you get from spice powder or garam masala. Make changes to the cooked ingredient to experience different tastes. Go ahead and try it. You dont have to wait for mid-night pangs to rummage your fridge and get a bite of this one.
Salt has to be added in little or no quantity to the sandwich filling because every other ingredient like sauces, mayonnaise and leftover sabzi contains salt. Toast the sandwich as much as you like, adding a little butter on both sides (if required). Toasting over low heat for longer duration gives best results but if you are too hungry to wait then just warming the bread will also do. Please do not press the bread while toasting as that could spoil the texture.