Preheat oven to 350°F (175°C). Grease two 9-inch round cake pans. Line with parchment paper, and grease paper.
Whisk together the cake flour, baking powder, and salt. Set aside.
Using an electric mixer on medium speed, beat the butter and sugar until light and fluffy. Add the eggs, one at a time, mixing well after each addition. Mix in the citrus zest.
Combine the citrus juices.
Add about 1/3 of the flour mixture to the butter mixture, mixing just until combined. Mix in half of the combined juices. Alternate adding the flour mixture and the juices, ending with the flour. Mix just until combined.
Divide the batter between the prepared pans. Spread evenly and smooth the tops. Bake 25 to 35 minutes, or until a pick inserted into the center comes out clean. Cool the cake layers completely.
To make the frosting:
Using an electric mixer on medium speed, beat the cream cheese and butter until thoroughly combined. Mix in the Tequila and lime juice.
Gradually add the confectioners' sugar, and mix until light and fluffy. Place one cooled cake layer on a cake plate, and frost the top. Place the other cake layer on top of the frosted layer. Frost the top, and then frost the sides of the cake.
Garnish the frosted cake with sea salt.
Notes
Store in an airtight container in the refrigerator up to 5 days. Bring to room temperature for serving.
Note that the tequila flavor may intensify over time in the frosting