01 - Slice the calamari tubes into ½-inch rings and pat dry with paper towels.
02 - Combine calamari with buttermilk, 1 tsp salt, and ½ tsp black pepper in a bowl. Refrigerate for 15 minutes to marinate.
03 - Heat olive oil over medium heat in a saucepan. Add garlic and sauté until fragrant, about 1 minute. Stir in crushed tomatoes, oregano, basil, red pepper flakes, sugar, salt, and pepper. Simmer uncovered for 10 to 12 minutes, stirring occasionally. Adjust seasoning as needed and keep warm.
04 - In a shallow bowl, combine flour, cornstarch, smoked paprika, garlic powder, cayenne pepper, and ½ tsp salt.
05 - Heat vegetable oil to 350°F (180°C) in a deep pot or fryer.
06 - Remove calamari from marinade, allowing excess buttermilk to drip off. Dredge calamari in the breading mixture, coating thoroughly and shaking off excess.
07 - Fry calamari in batches for 1½ to 2 minutes until golden and crisp, avoiding overcrowding.
08 - Drain calamari on paper towels and season lightly with salt while still hot.
09 - Serve immediately with warm marinara sauce, lemon wedges, and a sprinkle of fresh parsley if desired.