Squid in its ink

Name: Squid in its ink
Ingredients: ½ cup (4 fl oz/120 ml) olive oil; 10 squid (about 2¼ lb /1 kg total), head, tentacles, and body separated, ink sacs removed from the head, tentacles discarded, quill removed, and body cut into rins; 4 cloves garlic, finely chopped; 4 tablespoons chopped parsley; 1 cup (8 fl oz/240 ml) dry white wine; 1 teaspoon vinegar; 1½ teaspoons salt; ⅛ teaspoon ground black pepper; s 1 large white onion, finely chopped