1 3/4 cups all-purpose flour
2 teaspoons baking powder
1/2 teaspoon salt
2 tablespoons butter, softened
3 tablespoons vegetable oil
1 cup granulated sugar
2 large eggs, lightly beaten
1 1/2 teaspoon grated key lime zest
1 tablespoon fresh key lime juice
2/3 cup buttermilk
1 cup powdered sugar
1/2 cup fresh key lime juice
Preheat oven to 350°F (175°C). Grease a 9-inch spring form tube pan and set aside.
In a small mixing bowl, stir together the flour, baking powder, and salt. Set aside.
In a large mixing bowl, cream together butter and oil with a mixer until well blended. Gradually add sugar and beat until blended. Beat in the eggs, lime zest, and juice.
Alternately stir into the creamed mixture the flour mixture and buttermilk. Mix well.
Pour batter into the pan and bake for about 50 minutes or until wooden pick inserted in center comes out clean.
To make the syrup, whisk together the powdered sugar and the lime juice.
While the cake is still warm, poke holes in it using the tines of a serving fork. Spoon the lime syrup evenly over the cake. Cool completely and dust with additional powdered sugar.