In a mixing bowl put boiled and mashed potatoes, mashed paneer, red chilly flakes, oregano, salt, mozzarella cheese, chopped coriander leaves and mix it well until all the spices gets combined.
Stuffing is ready, keep aside.
Peel and slice the onion into 1-inch thick rings, and separate the rings from each other.
Take a generous amount of stuffing and press it into the bottom of the onion ring and make it flat.
Repeat the same process to make rest of the onion rings.
To make flour paste put cornflour, all purpose flour, salt in a bowl and make a thin batter by using water. Mix it well and make sure there should be no lumps.
Dip one by one stuffed onion rings into the flour paste, shake it off to remove excess paste and then coat it with bread crumbs all around.
Dip and coat all the stuffed onion rings in the same manner.
I am going to fry it instantly but if you have so much time then you can keep it in fridge also to make the mixture firm.
Heat oil in deep pan on medium high heat, once the oil becomes hot drop the stuffed onion rings slowly into it, taking care not to overlap them. Fry stuffed onion rings in batches, do not overcrowd the pan
Fry the stuffed onion rings until they are golden brown, turning occasionally. This would take about 3-4 minutes. Take them out over a paper towel or an absorbent paper to remove excess oil.
Crispy stuffed onion rings are ready.
Serve hot with any green chutney or tomato ketchup.