If you love bold flavors and dishes that taste traditional, this recipe for Mackerel with Sweet and Sour Onions will win you over at the first taste.
Mackerel, king of the blue fish for its properties and intense flavor, meets the queen of onions: the Red of Tropea.
The secret of this dish lies in the contrast: the saltiness of the fish, made crispy by a light flouring, perfectly marries the softness of the onions slowly stewed and deglazed with sweet and sour.
It’s a main dish poor in name only, but rich in character, perfect to enjoy either warm or cold (in fact, it’s even better the next day!). Get ready, because dipping bread in the onion sauce is practically mandatory!
Below as always, I leave you other tempting recipes to try and then we’ll get right under the picture to discover what we need to prepare the Mackerel with Sweet and Sour Onions😉
See you soon with the next recipe, Ana Amalia!
- Difficulty: Medium
- Cost: Very Economical
- Preparation time: 20 Minutes
- Portions: 4People
- Cooking methods: Stovetop
- Cuisine: Italian
- Seasonality: All Seasons
Ingredients for Mackerel with Sweet and Sour Onions
- 4 mackerels (medium-large)
- 5 Tropea red onions
- 1 tablespoon sugar
- 1 tablespoon white wine vinegar
- to taste flour (for dusting the fish)
- 4 tablespoons extra virgin olive oil
- 1 chili pepper
- 2 pinches salt
- to taste parsley
Preparation of Mackerel with Sweet and Sour Onions
1. How to Fillet the Mackerel: Don’t be scared: filleting the fish just requires a bit of attention and a sharp, flexible blade knife.
Start by making a clean cut behind the head and one along the belly to remove the guts. Rinse it well under running water.
Place the fish on the cutting board and, starting from the head, slide the blade along the backbone down to the tail. This will give you the first fillet.
Turn the fish over and repeat the operation on the other side.
Trim the fillets by removing the fins and, using kitchen tweezers, remove the small central bones that you feel when running your fingertip over the flesh.2. Cooking the Onions (the secret to softness): To get soft and transparent onions without burning them, patience is needed:
Slice the onions not too thinly (about 3-4mm or 1/8 inch).In a large pan, heat a generous swirl of extra virgin olive oil (about 2 tablespoons) with the chili pepper.
Add the onions and a pinch of salt. Cover with a lid and cook on very low heat for about 15-20 minutes.The salt and steam will make them wilt gently without drying out. If you see they dry out too much, add a tablespoon of water.
When they become translucent and super soft, slightly raise the flame, add the sugar and vinegar. Let them evaporate for a couple of minutes until the pungent smell of vinegar disappears, then turn off the heat.
3. Cook the Mackerels: Dry the mackerel fillets well with paper towels (it’s crucial to make them crispy).
Pass them in the flour, shaking off the excess.In a separate pan, heat the remaining extra virgin olive oil and cook the fillets: always start from the skin side.
Let them cook for about 2-3 minutes until the skin is golden, then gently flip them and finish cooking for another 1-2 minutes. Salt only at the end.
4. Plate and Serve: Place the mackerel fillets on the serving plate or directly in the pan with the onions (if serving immediately).
Cover the fillets with the sweet and sour Tropea onions so the flavors blend perfectly.
A little extra tip:
If you have time, prepare the mackerel a few hours in advance. The rest period allows the fish’s flesh to absorb all the fragrance and aroma of the sweet and sour onions, making it even more flavorful!
Mackerel with Sweet and Sour Onions, Tips, Storage, and Variations
In the refrigerator: You can keep it in an airtight container for 2-3 days. We recommend preparing it at least a few hours in advance (or the day before) because the fish will perfectly absorb the aromas of the onion and vinegar.
Serving Tip: If you store it in the fridge, take it out at least 30 minutes before serving. It’s excellent at room temperature or slightly warmed, but not hot, to avoid ruining the sweet and sour balance.
Freezing: Freezing is not recommended for this dish, as the texture of the onion and the delicacy of the fish would suffer once thawed.
Freezing: Freezing is not recommended for this dish, as the texture of the onion and the delicacy of the fish would suffer once thawed.
Gourmet Variation: Add a handful of raisins (soaked in water) and toasted pine nuts to the onions halfway through cooking. You’ll get a version reminiscent of the famous Venetian “Sarde in Saor”.
Citrus Variation: Replace the white wine vinegar with orange or lemon juice. The result will be a more delicate and fragrant sweet and sour, perfect for those who don’t like the strong smell of vinegar.
White Onion: If you can’t find Tropea reds, you can use white or yellow onions, but add an extra pinch of sugar to compensate for the lesser natural sweetness compared to Tropeas.
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FAQ (Questions and Answers)
Does the mackerel have to be fresh, or can I use frozen?
Fresh fish has better texture and flavor, but you can also use frozen fillets. In that case, make sure to thaw them slowly in the refrigerator and dry them very thoroughly before dusting with flour, otherwise, they won’t become crispy.
Can I use apple cider vinegar instead of white wine vinegar?
Absolutely. Apple cider vinegar is milder and less pungent, so it’s a great alternative if you prefer a softer sweet and sour.
How do I know when the onions are cooked just right?
The onions should become translucent and “wilted,” meaning they should lose their initial firmness. If you touch them with a wooden spoon, they should feel tender and almost buttery. If you see the edges darken too quickly, the heat is too high: add a splash of water and lower immediately.
Is it necessary to remove the skin from the mackerel?
No, quite the contrary! The skin of the mackerel, once floured and browned, becomes delicious and helps keep the fillet compact during cooking. It’s crucial to start cooking the fish skin side down.
Can I prepare the onions in advance?
Yes, the sweet and sour onions can be prepared the day before and stored in the fridge. You’ll just need to warm them up in the pan while you cook the fish.
Is mackerel too strong-tasting, how can I tone it down?
Mackerel is naturally flavorful. If you want a milder taste, make sure to thoroughly remove the dark part (the blood) during cleaning and soak the fillets in ice water for 10 minutes before drying and flouring them.
