Pour oil into a large saucepan or deep fryer to a depth of 3 to 4 inches. Heat the oil to 350 degrees.
Gently clean the mushrooms with a damp paper towel. If these stems are very large (greater than 3/4 inch), trim off the stem, as they may be woody. If the mushrooms are small, there is no need to trim off the stem.
Combine the flour with the salt and pepper in a bowl. Stir to combine the flour mixture.
Combine buttermilk and water in another bowl
Dredge the mushrooms in the seasoned flour, shaking off the excess, and then dip them in the buttermilk.
Dredge them in the flour again. Knock off the excess flour.
Lower the mushrooms gently into the hot oil, cook them until they are golden brown. It will take about 2 to 3 minutes for the mushrooms to cook. Drain on a wire rack. Serve with your favorite sauce.
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Recipe Tips
Pro Tips for Perfect Fried Mushrooms
Room temperature buttermilk: Take the buttermilk out of the refrigerator 20-30 minutes before using. Room temperature buttermilk coats the mushrooms more evenly and creates a better crust.
Maintain oil temperature: Use a thermometer to keep the oil at 350°F. If the oil is too cool, the mushrooms will absorb too much oil and become greasy. If it's too hot, the coating will burn before the mushrooms cook through.
Work in small batches: Overcrowding the fryer will lower the oil temperature and result in soggy mushrooms. Fry in small batches, allowing the oil to return to temperature between batches.
Don't skip the double-dredge: The flour-buttermilk-flour process is key to achieving that thick, crispy coating that makes these mushrooms special.
Let them drain properly: Allowing excess oil to drain on a wire rack rather than paper towels keeps the bottom of the mushrooms from becoming soggy.