Peel mango and cut fruit away from pit. Discard pit. Puree mango flesh in food processor or blender with orange juice concentrate. In a bowl, stir yogurt until smooth and creamy (no lumps). Add sugar and pureed mango mixture and stir to blend thoroughly. Taste for sweetness. If it tastes perfect before freezing, add a pinch or two more sugar; flavors tend to diminish when frozen.