Begin by cleaning your fresh mushrooms with a damp cloth to remove any dirt, ensuring they are ready for cooking. Trim the stems as necessary and set the mushrooms aside on a plate, ready to be soaked for the next step, which adds flavor and helps the batter adhere.

In a mixing bowl, pour in the cultured buttermilk, making sure to fully submerge the cleaned mushrooms. Allow them to soak for 10 to 15 minutes, which not only enhances flavor but also creates a rich base for the crispy coating to stick to during frying.

While the mushrooms soak, prepare the seasoned flour mixture. In a separate bowl, whisk together all-purpose flour, kosher sea salt, black pepper, smoked paprika, garlic powder, and baking soda until evenly combined.

Once the mushrooms have soaked, remove them from the buttermilk and let any excess liquid drip off. Dredge each mushroom in the seasoned flour mixture, ensuring they are fully coated.

In a deep saucepan, pour enough vegetable oil to submerge the mushrooms, and heat it over medium heat until it reaches 350°F (175°C). To test the readiness of the oil, sprinkle a tiny bit of the flour mixture into the oil; it should sizzle immediately.

Carefully add the coated mushrooms to the hot oil in small batches, to avoid overcrowding. Fry them for about 3 to 4 minutes, turning gently as needed, until they are a glorious golden brown and crispy on the outside.

Using a slotted spoon, gently remove the fried mushrooms from the oil and let them drain on a plate lined with paper towels. Serve hot, paired with your favorite dipping sauce.