1Cut tops and bottoms from grapefruits and oranges, then cut along the pith to remove remaining skin. Cut between the membranes to remove citrus sections. Drain in strainer to remove excess juice.
2In 8 martini glasses, sorbet cups or coupes, layer as follows: First place 3 to 5 grapefruit sections, 3 mint leaves, then a heaping tablespoon of yogurt, then about 8 orange sections. Follow that with 2 more mint leaves, another heaping tablespoon of yogurt, then pistachio nuts.