In a small bowl, whisk together the yogurt, honey, liqueur, if using, and the mint. Set aside.
Scoop out the melon flesh and cut it into 1inch cubes. Combine them in a bowl or on a platter and toss together very gently until the colors are evenly distributed.
Drizzle the dressing back and forth across the melon in a thin stream. Garnish with sprigs of mint and serve.
c.1997, M.S. Milliken & S. Feniger, all rights reserved