Prepare the oysters:
- In a large bowl, whisk together buttermilk, 1 teaspoon of the cayenne, and 1 teaspoon of the salt. Add oysters and set aside in fridge.
- In another large bowl, combine cornmeal, flours, remaining 2 teaspoons of cayenne pepper, and remaining 2 teaspoons of salt. Mix thoroughly and set aside.
Make the fennel coleslaw:
- Combine first four ingredients in a large bowl and set aside.
- Whisk together remaining ingredients in a bowl to form a dressing. Add 1 cup dressing to the fennel-cabbage mixture, and stir to coat. Add additional dressing, if desired, and season with additional salt and pepper to taste. Set aside in fridge to let flavors meld while proceeding with recipe.
Fry the oysters:
- Bread oysters and hold in fridge.
- In a large skillet, heat peanut oil to 360 degrees. Working in batches of five to six oysters at a time, fry oysters until golden brown and cooked through, about 2 minutes. Serve alongside slaw.