1. Prepare the Calamari

1. If using frozen calamari, thaw completely and pat dry with paper towels to remove excess moisture.
2. Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the minced garlic and red chili flakes, cooking until fragrant, about 1 minute.
3. Add the calamari rings to the skillet and sauté for 2-3 minutes, or until they turn opaque and are just cooked through. Be careful not to overcook, as calamari becomes rubbery when overcooked.
4. Remove the calamari from the skillet and set aside.

2. Make the Puttanesca Sauce

1. In the same skillet, heat 2 tablespoons of olive oil over medium heat. Add the chopped onion and sauté until softened and translucent, about 5 minutes.
2. Add the minced garlic and cook for another minute until fragrant.
3. Stir in the crushed tomatoes, olives, capers, and anchovies (if using). Add the oregano, red chili flakes (if desired), and sugar. Stir well to combine.
4. Simmer the sauce for 10-15 minutes, stirring occasionally, until it thickens slightly and the flavors meld together.
5. Taste and adjust seasoning with salt and black pepper, keeping in mind that the olives, capers, and anchovies already contribute saltiness.

3. Combine the Calamari and Sauce

1. Return the cooked calamari to the skillet with the sauce. Gently toss to coat the calamari in the sauce.
2. Simmer for an additional 2-3 minutes to allow the calamari to absorb the flavors of the sauce.

4. Serve

1. If serving with pasta, cook the spaghetti or linguine according to the package instructions. Drain and toss with the calamari and Puttanesca sauce.
2. Alternatively, serve the calamari and sauce with crusty bread for dipping or spoon it over creamy polenta for a hearty, comforting meal.
3. Garnish with freshly chopped parsley and, if desired, a sprinkle of Parmesan cheese.