Ingredients 
1 1/4  cups all-purpose flour, plus more for dredging    
1/2  cup fine yellow cornmeal    
1/4  cup packed light-brown sugar    
1  tablespoon baking soda    
1 1/2  teaspoons coarse salt    
1  cup buttermilk, room temperature    
1  large egg, room temperature    
1  teaspoon pure vanilla extract 
Vegetable oil, for frying    
2  Gala apples, peeled, cored, and cut into 1/4-inch-thick rings 
Confectioners’ sugar, for dusting 
 
Directions
1.   Whisk together flour, cornmeal, brown sugar, baking soda, and salt in a large bowl. Whisk together buttermilk, egg, vanilla, and 3/4 cup water in another bowl. Add buttermilk mixture to flour mixture; stir to combine (batter will be lumpy).
    
2.   Heat about 4 inches oil in a medium cast-iron or heavy stockpot until it registers 360*F on a deep-fry thermometer. Dredge apple rings into flour, shaking off excess; then dip into batter. Working in small batches, fry, flipping once, until dark golden brown, about 2 minutes per side. Transfer to paper towels to drain. (Adjust heat between batches as needed to keep oil at a steady temperature.) Dust with confectioners’ sugar before serving.  Makes 1 1/2 dozen 

Source:   www.marthastewart.com