Preheat oven to 350.

Whisk together flour, baking powder and salt.

Combine next seven ingredients.

Gradually stir flour mixture into the yogurt mixture, then pour into a 9" round greased baking pan.

Bake until toothpick inserted in center of cake comes out clean, 25-30 minutes. Let cool.

For glaze, mix confectioners sugar with enough grapefruit juice to reach desired consistency; drizzle glaze over top, allowing some to flow over sides. Top the cake with grapefruit sections and fresh mint leaves.

To freeze: Omit glaze. Securely wrap cooled cake in plastic AND foil, then freeze. When ready to use, thaw at room temperature, and prepare glaze as directed above.