Pre-heat the oven to 180°C/350°F/Gas Mark 4. Sauté the mushrooms in 2 tablespoons of margarine with the crumbled vegetable stock cube. Remove from the heat and set aside. Place the finely chopped onion in a deep saucepan with 4 tablespoons of margarine. Cook slowly for 2-4 minutes, taking care the onion does not brown. Add the rice and cook on a medium heat stirring constantly. After a minute or so stir in ½pint / 300ml hot vegetable stock to which you have added the ground cumin. Continue cooking, adding stock as necessary and stirring from time to time, until the rice is almost cooked (15 minutes). Season with salt freshly ground pepper and crushed dried chilies to taste. Cut the reserved mushrooms into small pieces and fold carefully into the risotto. Stir in the freshly grated Parmesan if using. Serve with a mixed leaf salad. For special occasions - substitute vegetarian white wine for some of the liquid and top with torn Basil leaves.