In a saucepan, bring the water and milk to a boil. Stir in the oats, carrots, raisins, cinnamon, ginger, nutmeg and salt. Bring the mixture back to boil, then decrease the heat to low and partially cover the pot. Cook the porridge, without stirring, until it begins to thicken and the oats are soft yet chewy. Check the oat's texture by stirring them after 25 minutes of cooking (it might need a few more minutes of cooking). Remove from heat and stir in the coconut flakes, orange zest and vanilla. Add maple syrup (or other sweetener), to taste. Cover and let the oatmeal rest for 5 minutes before serving. Toast the walnut pieces in a pan over medium-low, tossing frequently, until the edges are golden and the walnuts smell nice and toasty. Serve the oatmeal with a sprinkling of walnuts and a splash of milk or a swirl of plain yogurt.