Mash boiled potatoes finely and mix it well with green coriander, green chillis, and salt.
Heat up a pan and add 1 tablespoon oil in it.
After heating up the oil put asafoetida, cumin, and coriander powder.
After this add mashed potato. Mix well in spices.
Cook in on medium flame for 2 minutes. Now off the flame.
Let it cool.
How to make the sandwich.
Now light up the flame and keep it on medium. Put a tawa on it.
Take a bread slice and spread the stuffing on it in a fine layer. Put the 2nd slice on it.
Keep ready all the bread slices.
Now put little bit oil on tawa and spread it evenly.
Pick one set of sandwich and grease it with little oil. Now spread 1 tablespoon milk on the bread and put it on the hot tawa. Same as grease 2nd set of sandwich with oil and spread 1 tablespoon milk on it.
Roast the sandwich until it goes golden brown.
Flip the sandwich on tawa. So that it can be roast on both sides.
Cut the sandwich diagonally.
Garnish it with butter.
And your spicy milk sandwich is ready. You can serve it with tea, Jam or chutney.