1. Preheat oven to 350 ºF.
2. Combine buttermilk and Dijon mustard.  Mix well.
3. Add turkey fillets to buttermilk mixture to marinate for 5–10 minutes while preparing cornbread.
4. Grind cornbread in a food processor, or use your fingers to make coarse crumbs. 
5. Place breadcrumbs on a baking sheet, and dry in a 300 °F oven or toaster oven for 4–5 minutes.  Do not brown.
6. Pour breadcrumbs into a dry, shallow dish.  Put egg white in a separate bowl.
7. Remove turkey from the buttermilk, and dip each fillet first in the egg white and then in the cornbread crumbs to coat.  Be sure to discard leftover buttermilk mixture and cornbread crumbs.
8. Place breaded turkey fillets on a baking sheet, and bake for 10–15 minutes (to a minimum internal temperature of 165 °F).
9. While the turkey is cooking, combine chicken broth, cornstarch, carrots, sage, an butter in a medium saucepan.  Bring to a boil over high heat, stirring occasionally. Lower temperature to a simmer.
10.  Simmer gently for about 5 minutes, or until the butter is melted, the sauce is thick, and the carrots are warm.
11. Serve each 3-ounce turkey fillet with 1 cup of carrots and sauce mixture. 

Tip: Try serving with a baked or roasted sweet potato.