Take a bowl. Add boil smashed potato, chopped onion, tomato, ginger-garlic and green chillies, Corriender and cumin powder and salt as per taste. Mix them well.
Afterthat, cut bread pcs in circle ( same size).
Apply thin layer of ketchup over bread and top up with potato mixture. Apply ketchup on the other bread and put it on top. Make other sandwiches with this process.
On the other plate, in the bread crumbs add 1 tsp chilli powder and 1/2 tsp salt.
Take an another bowl. Add 4 tsp flour and salt. Add water and make a thin Batter.
Dip the sandwiches into the Batter from all sides. Then coat them with Breadcrumbs.
Press gently with hands.
Then shallow fry them from both the sides till changes to crispy and golden brown.
You can cut them into 2 pcs and serve hot.
(grind the bread edges and make bread crums)
( I took 8 pcs of bread and made 4 bread coins)