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