Take 1 cup of pepperoncini peppers and drain them well.
Place onto several layers of paper towels and pat dry.
If necessary, cut squid bodies into 1/2″ rings and place in a large bowl with whole tentacles and prepared pepperoncini peppers.
Pour buttermilk over squid mixture and toss lightly to combine. Cover and refrigerate until ready to use (up to 6 hours).
Combine flour, cornmeal, salt, black and cayenne pepper in a large bowl and whisk well.
Line a baking sheet with paper towels.
Heat 3" of oil in a 4-quart Dutch oven over medium heat (or in a deep fryer) until it registers 4000° on a deep-fry thermometer.
Uncover and stir squid with a slotted spoon, then lift about half of squid pieces from buttermilk, allowing excess buttermilk to drip back into bowl.
Drop coated pieces into the dry mix.
With a separate, dry slotted spoon, toss squid pieces to coat evenly with the fry mix, lift them out, gently shake off excess coating, and transfer to a plate.
Bread remaining squid.
Heat a medium sauté pan over medium heat and add butter.
Once butter melts, add garlic, lemon zest and sauté for about 1 minutes, do not brown garlic. Immediately add lemon juice and reduce heat to medium-low. Keep warm while frying squid mixture.
When the oil is hot, carefully drop half the squid pieces into oil. If any of the pieces stick to the bottom of the pot, loosen with tongs. Turn squid occasionally to cook evenly; it will only take about 1 1/2 minutes until they are crisp and golden.
Fry remaining squid and drain.
Place calamari in a serving bowl and drizzle with warm butter mixture. Sprinkle with chopped parsley and serve immediately.