Preheat oven to 425 degrees F.
Grease an 8-inch square pan, cast iron skillet, or cornbread mold. In a medium bowl, combine cornmeal, flour, sugar, baking powder, and salt. To dry mixture, add egg, milk, sour cream, oil, and jalapenos and mix until smooth. Pour into prepared pan. Bake for 20 to 25 minutes, or until golden.