1. Heat oil in a pan and lightly brown the onions.
2. Add the tomatoes and cook till soft.
3. Then add the salt, mustard powder and chilli flakes, stir.
4. Add the mushrooms and saute for some time.
5. Now add the tomato sauce, mix and add the Wostershire sauce and vinegar.
6. Stir well and keep aside.
7. In a mixie, grind the bread into crumbs and keep aside.
8. Boil and grate the potatoes.
9. Keep aside to cool.
10. Now add the salt and butter to it, mix and knead with your hands.
11. Sprinkle 1 tbsp of maida and mix again.
12. Take small amounts of mashed potato and flatten them into round shapes.
13. Add a spoonful of the mushroom filling onto each of these, gently seal into rolls
14. Heat oil in a kadai for deep frying.
15. In the meantime make a thin maida batter with water in a bowl.
16. Now gently dip the potato rolls into the batter, then roll them over the bread crumbs.
17. Deep fry till crisp and brown.
18. Serve hot with ketchup.

Image: Flickr/creativecommons eatingeast