Place the rice and 4 cups of water in a non-stick saucepan and bring to a boil. Reduce heat and simmer for 20 minutes. Drain the excess water from the rice and return rice to the saucepan and add the milk and sugar. Cook over low heat for 40 minutes. Stir in the ground cardamom and the evaporated milk and cook 5 more minutes. Stir in pistachios. Pudding will thicken as it cools. Serve in dessert bowls and garnish with fresh mint sprigs, if desired.