Take one cup of flour in a bowl , add salt, oil and water and make dough (not very soft and not much hard.)Keep it aside.
Take one plastic. Put grated cheese, finely chopped green bell pepper, onion, chillies and black pepper powder on it cover plastic from all the sides and mix well all the ingredients by meshing them.
By this way of mixing you will get flavour of each ingredient. Divide them into 2 rectangular portions as per your sandwich size.
Make 4 rectangular portions of your dough and roll rectangle roti. You can roll round roti and mould it in rectangle shape too. Grease pan with little butter and cook well one side of roti and half cook other side of roti. Cook all the rotis like this way.
Now put your cheese chilly mixture on full cooked side of roti , put another roti on it.
Spread butter in a frying pan and cook your sandwich both the sides until it is bit crispy.