Special equipment: a deep-frying thermometer
For the homemade ranch dip: Add the buttermilk, mayonnaise, sour cream, garlic, salt, vinegar, pepper, onion powder and hot sauce to a food processor. Pulse until well combined and smooth. Add the parsley and dill and pulse 4 to 5 times to incorporate. Pour into a serving bowl and set aside.
For the spicy pickle fries: Pat the pickle spears dry and refrigerate until well chilled. Heat 2 inches of oil in a large heavy pot to 350 degrees F on a deep-frying thermometer. Line a plate with paper towels.
Combine the flour, cayenne and salt in a wide shallow bowl. Beat the eggs in another shallow bowl. Put the panko in a third shallow bowl.
Working with a few spears at a time, dredge the pickles in the flour and shake off the excess. Roll them in the egg to coat, then let the excess drip off before coating them thoroughly in panko. Carefully add half the pickles to the oil and fry until golden brown, about 1 minute. With a slotted spoon, transfer the pickles to the lined plate to drain. Repeat with the remaining pickle spears. Serve hot with ranch dip.