01 - Combine calamari rings with buttermilk and ½ teaspoon salt in a bowl. Toss to coat thoroughly and refrigerate for 15 to 20 minutes.
02 - In a shallow dish, blend all-purpose flour, cornmeal, paprika, black pepper, garlic powder, and ½ teaspoon salt until evenly mixed.
03 - Preheat vegetable oil in a deep fryer or heavy pot to 350°F (180°C).
04 - Heat olive oil in a small saucepan over medium heat. Sauté minced garlic until fragrant, about 1 minute. Stir in crushed tomatoes, oregano, red pepper flakes, sugar, salt, and pepper. Simmer gently for 10 minutes, stirring occasionally. Add fresh basil if desired and keep warm.
05 - Drain calamari from buttermilk, allowing excess to drip off. Dredge rings in the flour-cornmeal mixture, ensuring full coverage.
06 - Fry calamari in batches without overcrowding the oil, cooking for 1½ to 2 minutes until golden and crisp. Remove with a slotted spoon and drain on paper towels.
07 - Arrange fried calamari on a platter. Garnish with lemon wedges and chopped parsley. Serve immediately alongside warm marinara sauce.