Method
heat a pan/ kadai, add little oil, add soya if with gravy add it, as it gets hot, try to mash the soy or use vegetable masher, then add left-over rice , tomato sauce/ chutney, mix all well, as there will be salt in all, no need to add more as cheese also has salt.
Once all the ingredients come together and thick, remove from fire, add mozzarella cheese, as it will melt in the heat and get mixed well. You may check the taste, if need be add some chili pdr if you want it spicy.
Once cool, make small balls of the above mixture, if using egg, dip in beaten egg or in slurry, to coat the ball well, then roll the balls in breadcrumbs to coat it well.
You can lightly grease the baking tray and keep the balls and bake in preheated oven @ 425 F/ 200 C for 8-10 minutes till the balls are golden. OR
you can fry in air fryer too. If you neither have oven nor air-fryer, instead of shaping them as balls, flatten them like patties and shallow fry in a pan, using little oil.
Serve it hot with tomato sauce or chutney of your choice.