Hardboil the eggs if not already done so (see notes). Slice in half lengthwise and remove the yolks. Place the yolks in a separate mixing bowl.
In the bowl with the egg yolks, combine the mayo, mustard powder. Cajun seasoning, hot sauce, bell pepper, and celery. Use a fork to mash until desired consistency.
Place the filling in the fridge to allow it to set up to 1 hour.
While the egg filling is setting, prepare the oysters. Whisk together the cornstarch, cornmeal, chili powder, garlic powder, and thyme in a large mixing bowl. In another bowl, combine the egg and water together to create an egg wash. Dip the oysters into the cornstarch/cornmeal mixture, then into the egg, and back into the cornstarch/cornmeal.
Head a skillet over medium-high heat with grapeseed oil. The pan is ready when you can drop a pinch of the cornstarch/cornmeal mixture into the oil and it starts to sizzle. Place the battered oysters into the pan and allow to cook 1 minute per side or until browned. Drain on paper towels to remove excess oil.
To fill the eggs, take a Ziploc bag and cut off a small corner (make sure the hole is big enough for the pepper & celery to fit through, otherwise it will clog the bag). Squeeze the bag to get the filling into the eggs. If you’re feeling fancy, use a pastry bag with a star nozzle.
Top with a freshly fried oyster and enjoy!
Optional to top with a few shakes of your favorite Southern-style hot sauce