01 - Place calamari rings and tentacles in a bowl with buttermilk, salt, and black pepper. Toss well, cover, and refrigerate for 15 minutes.
02 - Heat olive oil in a saucepan over medium heat. Add onion and cook until soft, about 3 minutes. Add garlic and sauté for 30 seconds.
03 - Pour in crushed tomatoes, oregano, red pepper flakes, sugar, salt, and black pepper. Simmer for 10-12 minutes, stirring occasionally. Stir in basil and adjust seasoning as needed. Keep warm.
04 - In a shallow bowl, mix flour, cornmeal, paprika, cayenne, and garlic powder until well combined.
05 - Heat vegetable oil in a deep pan or fryer to 350°F.
06 - Remove calamari from marinade, shake off excess buttermilk, and dredge in the flour mixture until well coated.
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 with warm marinara sauce, lemon wedges, and a sprinkle of fresh parsley if desired.