Prepare the mushrooms: Clean the mushrooms with a damp cloth and trim the stems. Set them aside.
Soak in buttermilk: In a large bowl, mix buttermilk and hot sauce. Add the mushrooms to the mixture, ensuring they are fully submerged. Let them soak for at least 30 minutes.
Prepare the dry mixture: In a separate shallow dish, combine flour, cornmeal, garlic powder, onion powder, smoked paprika, cayenne pepper, salt, and pepper. Mix well.
Coat the mushrooms: Remove mushrooms from the buttermilk, allowing excess liquid to drip off. Roll them in the dry mixture, ensuring an even coating.
Heat the oil: In a deep skillet or Dutch oven, heat the oil to 350°F (175°C). The oil should be enough to submerge the mushrooms.
Fry the mushrooms: Fry the coated mushrooms in batches, ensuring not to overcrowd the pan. Cook for about 4-5 minutes until golden brown and crispy. Remove with a slotted spoon and drain on paper towels.
Serve: Serve immediately with a dipping sauce of your choice, like ranch or spicy ketchup.