Fried Shrimp And Oyster Po'boy

Ingredients

• 12 shucked oysters
• 12 jumbo shrimp, peeled and deveined
• cornmeal dredge (recipe follows)
• peanut oil, for frying
• 1 small red onion, sliced thin
• 1 ripe tomato, sliced thin
• 1 teaspoon sherry vinegar
• 1 teaspoon prepared horseradish
• 1/2 teaspoon kosher salt
• 1/4 teaspoon black pepper
• 1 1/2 cups corn flour
• 1 1/2 cups corn meal
• 3 tablespoons popcorn salt
• 2 tablespoons onion powder
• 1 tablespoon granulated garlic
• 1 tablespoon white pepper
• 2 teaspoons cayenne pepper
• 1 teaspoon celery salt
• 4 egg yolks
• 2 tablespoons dijon mustard
• 1/4 cup steen's cane vinegar
• 2 teaspoons kosher salt
• 2 cups canola oil
• 1 12-inch crusty french roll