Prepare the Sardines: Season the sardine fillets with salt and pepper. Lightly dust them with flour, shaking off any exce

Fry the Sardines: Heat half of the olive oil in a large frying pan over medium-high heat. Fry the sardines in batches until golden and crisp, about 1-2 minutes per side. Transfer to a paper towel-lined plate to drain.

Sauté the Onions: In the same pan, add the remaining olive oil and reduce the heat to medium. Add the onions with a pinch of salt and cook, stirring occasionally, until they are soft and golden, about 15-20 minutes.

Add Vinegar and Water: Increase the heat to medium-high, and add the vinegar and water to the onions. Bring to a boil, then reduce the heat and simmer for 5 minutes. Remove from heat and let cool slightly.

Marinate: In a glass dish, create layers of the fried sardines and the onion mixture. Sprinkle each layer with pine nuts and raisins. Continue layering until all ingredients are used.

Refrigerate: Cover and refrigerate for at least 24 hours, allowing the flavors to meld. The dish can be stored in the refrigerator for up to 3 days.

Serve: Bring the sardines to room temperature before serving. Garnish with fresh parsley.