1. Heat oven to 400 degrees. Grease "cake pan", 13x9x2.
2. Put buttermilk (or 1/3 cup milk mixed with 1 tsp lemon juice or vinegar) in bowl; put cornmeal and taco seasoning in large plastic bag.
3. Dip chicken in buttermilk, then place in bag and shake to cover in cornmeal mixture. Place in pan. Drizzle with oil.
4. Bake uncovered 40-45 min, turning once, until juice of chicken is no longer pink when centers of thickest pieces are cut.