Add about 1 tablespoon of vegetable oil to a 10-inch seasoned iron skillet; place in oven.
In a mixing bowl, combine the meal, flour, salt, baking powder and soda.
In another bowl, whisk buttermilk and milk with eggs and melted butter.
Gradually fold milk mixture into dry ingredients, folding and mixing just until all dry ingredients are moist.
Using oven mitts or potholders, carefully remove the hot skillet from the oven; swirl slightly so oil coats sides of pan. Pour batter into the skillet then return to oven. Reduce heat to 350°. Bake cornbread for 35 to 45 minutes, until it pulls away from sides of pan and is lightly browned.
Cut into squares or wedges.
Place desired amount of cornbread and onion into glass of milk, and mix with spoon.