Cut the squid into rings and let rest in a bowl of milk for 5 minutes. To make the batter: Mix the flour, bread crumbs, salt, and black pepper in a bowl. Remove the calamari from the milk bath, making sure you allow the milk to drip out, and add the calamari to the flour mixture. Mix the calamari in the batter with your hands making sure all the rings are evenly coated. Remove the calamari from the batter onto a plate and shake off any excess flour. Heat up the extra-virgin olive oil in a deep pan. Keep the temperature at a high and gently place some of the calamari in the hot oil, making sure they are not crowded. Fry until golden brown and crisp. With a slotted spoon, transfer the calamari to a plate and place on an absorbent paper towel. Sprinkle the calamari with salt, while hot.