Whisk together the mayonnaise, buttermilk, and Hidden Valley Ranch Seasoning until smooth. Refrigerate while preparing the scallion fries.

Heat 3 to 4 inches of neutral oil in a heavy pot or Dutch oven to 350°F (175°C).

In a large bowl, whisk together the club soda, egg, salt, and 1 cup flour. Continue adding flour a little at a time until the batter is thinner than pancake batter but slightly thicker than tempura batter. It should coat the scallions evenly without being overly thick.

Wash and pat dry scallions. Cut off the roots of the scallions. Use only the thick white and light green parts of the scallions. The dark green tops are too thin and delicate to fry. Lightly coat the scallions with flour before dipping in batter. Dip each scallion into the batter, allowing any excess to drip off.

Working in small batches, carefully fry the battered scallions for 2 to 3 minutes, or until lightly golden. Do not overcrowd the pot, as this lowers the oil temperature and prevents the batter from becoming crispy. Add drizzles of batter over the fries to create a crispy craggly texture. Transfer to a wire rack while frying the remaining batches.

Increase the oil temperature back to 375°F (190°C). Fry the scallions a second time for 1 to 2 minutes, or until deeply golden and extra crispy. This second fry helps lock in the crunch and keeps the coating crisp for longer.

Immediately sprinkle with salt and cayenne pepper while they’re still hot.

Serve immediately with the homemade restaurant style ranch for dipping.