Pickled Ivasi Sardines with Onions

Far Eastern sardines, widely known in our region as Ivasi herring (Pacific sardines), are a delicious and healthy saltwater fish packed with Omega-3 fatty acids. Technically, Ivasi is not herring at all but a member of the sardine family, prized for its exceptionally tender texture and high fat content. Pickled Ivasi sardines with onions and apple cider vinegar boast a delicate spice aroma that enhances the natural flavor of the fish without overpowering it. This cold seafood appetizer is a true centerpiece: the silver-skinned fillets suspended in a crystal-clear marinade look incredibly appetizing and disappear from plates in a flash, especially when paired with steaming hot boiled potatoes.

Preparation: 15 minutes
Cooking: 72 hours
Quantity: 6 Servings
Per serving
Calories: 207 kcal
Proteins: 18.2 g
Fats: 14 g
Carbohydrates: 1.5 g

Ingredients

  • 4 salted Ivasi (Pacific sardines)
  • 1 large yellow onion
  • 3-4 bay leaves
  • A few whole black peppercorns and allspice berries
  • 4 whole cloves
  • 1 tsp coriander seeds
  • 50 ml (1.7 fl oz) apple cider vinegar
  • Filtered water

How to Make Pickled Ivasi Sardines with Onions

Select Ivasi (Pacific sardines) exactly as you would regular herring. The fish should be firm, the skin free of rust-colored spots, and the eyes clear. Ivasi differs from regular herring in size, and you will notice characteristic black spots along its back.

Fresh whole Ivasi sardines on a wooden cutting board

When selecting sardines, look for firm fish with unblemished skin.

Prep the sardines. Cut off the heads and tails, gut the fish, and thoroughly rinse the cleaned cavities under cold running water. Never wash fish with warm or hot water!

Cleaned headless Ivasi sardines prepared for filleting

After gutting, always rinse the fish with ice-cold water to preserve its texture.

Score the fish along the spine using a sharp knife. Peel the skin off. Carefully separate the fillets from the backbone. Pluck out any visible pin bones.

Clean Ivasi sardine fillets separated from the bones

Carefully remove the backbone and any pin bones to yield clean fillets.

If the salted Ivasi is overwhelmingly salty, place the cleaned fillets in a bowl, cover with cold filtered or boiled water, and let soak for 20-30 minutes to draw out excess salt. Skip this step if your sardines are lightly salted.

Sardine fillets soaking in a bowl of cold water

If the fish is too salty, a 20-30 minute soak in cold water will draw out the excess salt.

While the fish is soaking, prep the marinade. Toss whole black peppercorns, allspice berries, and coriander seeds into a saucepan. Add bay leaves and whole cloves.

Coriander, peppercorns, and bay leaves in a metal saucepan

Coriander, peppercorns, and bay leaves make up the classic aromatic marinade base.

Remove the fillets from the water, transfer to paper towels, and pat completely dry.

Sardine fillets resting on white paper towels

Thoroughly pat the fillets dry with a paper towel so they absorb the marinade perfectly.

Pour 150 ml (5 fl oz) of water into the saucepan. Add a pinch of sea salt if the fish is only lightly salted, and bring to a boil. Simmer for 5 minutes.

Spiced marinade simmering in a saucepan on the stove

Simmer the spices for 5 minutes to fully extract their flavor and aroma into the water.

Dice a large yellow onion into small cubes. Drop the diced onion into the boiling marinade. Bring everything back to a boil. Simmer for exactly 2 minutes, then immediately pour in the apple cider vinegar.

Diced onions added to the boiling spiced marinade

The onions should only blanch slightly in the boiling liquid to retain their crunch.

Cool the prepared onion marinade down to room temperature. Never pour hot marinade over the fish, or it will cook!

Cooled onion and spice marinade in a saucepan

It is crucial to cool the marinade completely before pouring it over the fish.

Slice the cleaned sardine fillets into bite-sized pieces. Grab a suitably sized glass jar. Arrange an even layer of fish pieces at the bottom.

Bite-sized pieces of fish at the bottom of a glass jar

Begin filling the jar by arranging the fish pieces in an even layer.

Spoon a layer of the pickled onions and spices over the fish. Continue layering the jar all the way to the top, alternating between fish and onions.

Pickled onions spooned over fish layers in a glass jar

Evenly distribute the pickled onions between the layers of fish.

Pack the jar loosely. Pour in the remaining liquid to ensure the contents are completely submerged in the marinade. Seal the jar tightly and refrigerate. The fish will be ready to taste in about 3 days. Bon appétit!

Glass jar filled with pickled Ivasi sardines and onions

After three days in the fridge, the sardines become incredibly flavorful and tender.

The ultimate simple sandwich: a thin slice of dark rye bread, topped with a thin round of boiled potato, a piece of pickled Ivasi (Pacific sardine), and a generous mound of those marinated onions. It is pure comfort food that makes your mouth water just looking at it! Absolutely delicious! To elevate the flavors even further, try sprinkling some finely chopped fresh dill or adding a few drops of aromatic unrefined sunflower oil right before serving. If you love experimenting, toss a few thin carrot rounds or celery root slices into the jar—they will infuse the marinade with lovely sweet undertones. Pickled Ivasi keeps beautifully in the fridge for up to a week, the flavors deepening day by day. Just ensure the marinade completely covers the fish; this prevents the surface from drying out and keeps the fillet texture flawlessly tender.