Spray a small frying pan with low calorie cooking spray and place over a medium heat. Add the onion and fry for 4 - 5 minutes, stirring occasionally, until golden.
Add the garlic, ginger, chilli powder, ground coriander, garam masala and cumin. Stir in and cook for 1 - 2 minutes.
Add the lamb and cook for a few minutes until sealed and brown all over. Stir in the tomato puree and water and gently simmer over a low heat for 10 - 12 minutes until all the liquid has evaporated off and the meat mixture is dry.
Stir in the fresh coriander and season with salt and pepper. Set aside and leave to cool.
Pre-heat the oven to 200ºC.
Sift the flour, sugar, salt and baking powder into a large bowl.
Make a well in the centre and add the yoghurt. Using your fingertips, gradually draw the flour into the yoghurt, mixing to form a ball of soft dough.
Place the dough on a lightly floured surface and knead well for 5 minutes. Place the dough in a lightly greased large bowl, cover with cling film and leave in a warm place for approximately 45 minutes until the dough has increased slightly in size and feels slightly puffy when pressed.
Turn out onto a lightly floured surface and, using a sharp knife, cut into 4 equal pieces. Shape each piece into a ball, then roll each one out into a small disc approximately 10cm in diameter.
Place 2 tbsp of the keema mixture in the centre of each disc of dough. Pull up the edges of the dough to seal the keema mixture inside, pressing together to seal.
Form into four oval balls and turn over, placing seam side down on a lightly floured surface. Using a rolling pin, roll into four oval shaped naan, each one approximately 22cm x 11cm.
Place the keema naan on two lightly greased baking trays and prick with a fork.
Place in the preheated oven for 7 - 8 minutes or until golden and puffy. Remove from the baking trays and place on a cooling rack.
Place the reduced fat spread in a small saucepan, and place over a very low heat. Heat until just melted, then use to brush over the warm keema naan breads.
Serve at once while still warm. If wished, sprinkle with a little chopped fresh coriander.