Whisk together the eggs and buttermilk, in a large bowl. In a separate bowl, whisk together the cornmeal, flour, baking soda, salt, and sugar. Add the wet ingredients to the dry ingredients, then add the onion and jalapenos and stir until incorporated and the batter is thick.
1 cup Cornmeal, 3/4 cup All-purpose flour, 3 teaspoons Baking powder, 1 teaspoon Salt, 1 tablespoon Granulated sugar, 1/4 teaspoon Baking soda, 2 large Eggs, beaten, 1/2 cup Buttermilk, 1/4 cup Onion, 1/4 to 1/2 cup Jalapeno peppers