THE CRUST: Cook the rice for about 45 minutes in boiling water, or until quite soft; drain well but do not rinse; mix all the crust ingredients together and press into the base and sides of a lightly oiled 10 inch flan dish and chill while making the filling.
THE FILLING: Heat the oil in a non-stick pan and, over a low heat, sauté the leeks and garlic slowly for about 15 minutes; add the baby spinach leaves and sauté until they have just wilted, about 2 minutes. Set aside.
In another pan, blend the oil and flour and heat gently until bubbly, then stir in the milk or soy milk, tamari and freshly ground pepper.
Bring to the boil and cook, while stirring, to make a thick white sauce. Combine the leeks mixture and the sauce, and pour the mixture into the pie crust.
Bake in a moderate oven for 15-20 minutes. If you want a golden crisp topping, add the (optional) grated cheese in the last 5 minutes of baking. Or if you'd like some extra flavour and crunch, add the (optional) pine nuts in the last 5 minutes of baking.
NOTES: Tahini (one of the ingredients in most hummus recipes) is made from ground sesame seeds, and tamari is a pure form of soy sauce, free of chemicals and preservatives. Tamari can be used in any recipe instead of stock cubes. Both tahini and tamari are available in health food stores and larger supermarkets.