Pre-heat the oven to 200°C and line a baking tray with non-stick baking paper.
Spray a saucepan with low calorie cooking spray and set on a medium heat. Gently fry the onions and garlic for a few minutes.
Add the carrot, potato, garlic granules, onion granules, stock, garam masala, curry powder, and soy sauce to the pan and bring to the boil. Then reduce the heat to a simmer and put a lid on the pan. It will need to simmer for around 20-30 minutes, make sure to stir occasionally and add more water if it reduces too much.
While the sauce is simmering, add the panko breadcrumbs to a bowl and the beaten egg to another.
Lay the chicken breasts out on a chopping board and using a sharp knife slice horizontally to create two smaller fillets.
Dip each chicken breast fillet into the egg and then the panko breadcrumbs and lay them out on the baking tray.
Spray the top of the chicken with low calorie cooking spray and place the tray into the oven. Cook for 30 minutes turning halfway through until the chicken is cooked through and no pinkness remains.
When the vegetables are cooked through, add the sweetener to the pan and use a hand blender to blitz until smooth.
Combine the salad ingredients together in a bowl.
Spread a little of the katsu sauce on the bottom of the roll and top with a cooked chicken fillet. Add some more sauce on top of the chicken fillet and top with some salad. Place a bread roll half on top. Serve with your choice of accompaniment.