To make the garam masala, place all the spices in a dry frying pan and shake over medium heat for 1 minute or until fragrant. Blend in a spice grinder, blender or mortar and pestle to make a fine powder. Heat the oil in a large saucepan. Add the onion, garlic and 3 teaspoons of garam masala. Cook over medium heat for 3 minutes, or until soft. Stir in the rice and lentils and cook for 2 minutes. Add the hot stock and stir well. Slowly bring to the boil, then reduce the heat and simmer, covered, for 15-20 minutes, or until the rice is cooked and all the stock has been absorbed. Gently fluff the rice with a fork. Garnish with spring onion.