Slice the cleaned squid tubes into rings about 1/2 inch thick and leave the tentacles whole if they are small, or cut them in half if large.

Place the squid rings and tentacles in a bowl and pour the buttermilk over them, letting them soak for 10 to 15 minutes to tenderize the meat.

In a large shallow dish, whisk together the all-purpose flour, cornstarch, garlic powder, salt, black pepper, and paprika until well combined.

Heat about 2 inches of vegetable oil in a heavy-bottomed pot or Dutch oven to 375°F (190°C), using a thermometer to ensure accuracy.

Remove a handful of squid from the buttermilk, shaking off the excess liquid, and toss them into the flour mixture to coat thoroughly.

Shake off any excess flour from the squid and carefully lower them into the hot oil, frying in small batches to avoid overcrowding the pot.

Fry for 2 to 3 minutes, or until the coating is golden brown and crispy and the squid is cooked through.

Remove the fried calamari with a slotted spoon and transfer to a paper towel-lined plate or a wire rack to drain excess oil.

Immediately sprinkle the hot calamari with a pinch of salt while it is still warm to ensure the seasoning sticks.

Serve the crispy calamari immediately on a platter with fresh lemon wedges for squeezing and a side of marinara sauce for dipping.