Preheat the oven to 350F. In a small bowl, whisk together the cake flour, baking powder, and salt. In a seperate bowl, beat the eggs together with the sour cream and vanilla. In a large mixing bowl, use a hand-held mixer on medium speed, cream together the butter and granulated sugar until well blended. Beat in about a third of the egg mixture.
Then half of the dry ingredients; then another third of the eggs, then the remaining dry ingredients; and finally the remaining egg mixture until completely blended.
Divide the batter equally among muffin pan. Bake until the tops spring back when lightly tapped, 20-25 minutes. cool on a wire rack for 5 minutes.
Meanwhile, in a small bowl, stir together the confectioners sugar and lemon and lime juices and zests. Turn out the cupcakes, place the wire rack over a sheet of wax paper, and return them to the rack. Spoon citrus glaze generously over the warm cupcakes, allowing some to run down the sides. Serve warm or cooled.