Put all the ingredients in the jar of a blender and blend till smooth. Empty it out into a freezer safe bowl, cover and put it in the freezer. After about 45 minutes to an hour, take it out and whisk vigorously (or use a hand blender) to break up the crystals.
Put the yogurt back in the freezer. Repeat the whisking a couple of times at hourly intrvals for a smoother textured Mango Yogurt.
Let the Mango Yogurt freeze. To serve, scoop out the Mango Yogurt into serving bowls and top with chopped pistachios and mint, or serve it plain or however you like it.