Put 1 tablespoon of the oil into a medium sized saucepan over a medium heat and add the chilli flakes, garam masala, sugar, garlic granules, turmeric, lo-salt and chopped tomatoes. Cook and stir for 4 to 5 minutes until the tomatoes soften. Be careful not to burn the spices.
Add the cubed chicken and stir to coat in the spices. Cook for 3 to 4 minutes to brown the chicken, then add the water and stir. Add the yoghurt and stir again to combine. Reduce the heat to a simmer and cook for around 10 minutes until the chicken is cooked through.
While the chicken is cooking. Heat the remaining oil in a medium sized saucepan and add the onion and green pepper. Cook over a high heat for 5 minutes or so until beginning to brown. Then add the quartered tomatoes and continue to cook, stirring for a further 3 minutes.
Mix the cornflour with a little water to make a thin paste and add to the chicken; stir until thickened a little. Then add the onion, green pepper and tomatoes from the other pan. Stir it all together gently.
Serve with rice, naan bread, chutney, etc. and enjoy.
Serves 4 people and is approximately 320 calories per serving without the rice or any accompaniments. The heat can easily be adjusted by subtracting or adding chilli flakes to personal taste - or of course, you could use fresh chillies.