01 - Slice calamari tubes into 0.5-inch rings; pat dry with paper towels.
02 - Combine calamari with buttermilk, 1 teaspoon salt, and 0.5 teaspoon black pepper; refrigerate for 15 minutes.
03 - Heat olive oil over medium heat, sauté garlic until fragrant, about 1 minute. Add crushed tomatoes, oregano, basil, red pepper flakes, sugar, salt, and pepper. Simmer uncovered for 10 to 12 minutes, stirring occasionally. Adjust seasoning and keep warm.
04 - In a shallow bowl, combine flour, cornstarch, smoked paprika, garlic powder, cayenne pepper, and 0.5 teaspoon salt.
05 - Heat vegetable oil in a deep fryer or pot to 350°F (180°C).
06 - Remove calamari from marinade, letting excess drip off. Dredge in flour mixture, coating evenly and shaking off excess.
07 - Fry calamari in batches for 1.5 to 2 minutes until golden and crisp. Avoid overcrowding.
08 - Drain calamari on paper towels; season lightly with salt while hot.
09 - Serve immediately with warm marinara, lemon wedges, and chopped parsley if desired.