01 - Toss calamari rings with buttermilk, salt, and pepper in a bowl. Cover and refrigerate for 15 minutes to tenderize the squid.
02 - Heat olive oil in a saucepan over medium heat. Add onion and garlic; sauté until translucent, about 3 minutes.
03 - Stir in crushed tomatoes, oregano, basil, sugar, salt, and pepper. Simmer for 10–12 minutes, stirring occasionally. Adjust seasoning, then set aside and keep warm.
04 - Combine flour, cornmeal, paprika, garlic powder, and cayenne in a shallow dish.
05 - Heat oil in a deep fryer or large heavy saucepan to 350°F.
06 - Remove calamari from buttermilk, letting excess drip off. Dredge rings in flour mixture, coating thoroughly.
07 - Fry calamari in batches for 1–2 minutes, until golden and crisp. Do not overcrowd the pan. Remove with a slotted spoon and drain on paper towels.
08 - Serve hot, garnished with parsley and lemon wedges, alongside marinara sauce for dipping.