Basque Kitchen Restaurant *, Singapore (Singapore)
Lubina Aquanaria a la Koskera


  • 1 piece of Aquanaria Sea Bass weighing 2-3 kg
  •  6 kg Live blue mussels
  •  6kg Live cockles
  •  Clams to plate
  •  100g Sea lettuce
  •   150g Brine
  •  4.5kg White onion
  •  230g White wine
  •  50g Leek
  •  110 g White mushrooms
  •  2 White asparagus
  •  200g Italian parsley
  •  30 g Chopped parsley
  •  100g tear peas from Getaria
  •  120g Egg white
  •  60g Kuzu
  •  Boiled quail’s egg
  •  Salt
  •  Garlic
  •  Olive oil
  •  Water


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This recipe for Aquanaria sea bass in koskera sauce comes from Singapore, where chef Aitor Jeronimo Orive has had a project of his own since 2018: the restaurant Basque Kitchen with a Michelin star. Aitor, Basque by birth, grew up in Madrid and Australia and before arriving in this Asian country worked in well-known restaurants such as Mugaritz, Fat Duck and Nerua. His restaurant includes two concepts: one gourmet and one based on pintxos, through which he honours his origins. 

Aquanaria sea bass is found in  restaurants in more than 22 countries worldwide. It is fished daily and thanks to an incredible logistics system,it arrives fresh, in a few days from Gran Canaria to all destinations however far away they may be. In the following video you can find out more.


Koskera sauce is also known as salsa verde or Basque sauce. It is a sauce traditionally made with large quantities of parsley, garlic, wine, peas, asparagus and boiled egg. The name is believed to have come from “koskeros”, the name given to residents of Donosti. The fish most commonly cooked in this way is hake.

In this recipe for sea bass with Koskera sauce, Chef Aitor cooks a gourmet version of this creation applied to Aquanaria’s product. A very elaborate and flavourful fish and seafood base, and garnished with peas from Guetaria, honouring his region of origin. 


Preparing the sea bass

  • Remove the scales of the fish and fillet, taking care not to break the flesh. 
  • Remove the stomach area and keep for other recipes. Keep the bones and head for stock. 
  • Place in seaweed brine for 9 minutes, then divide the fish into 150-200 g portions and put aside. 

Preparing the seaweed brine

  • Mix the sea lettuce, brine and 3 litres of water
  • Beat with a handheld blender until finely chopped. 
  • Strain and put to one side.

Preparing the mussel stock 

  • Wash and clean mussels and cockles
  • Cut  2 kilos of onions into julienne strips, then sweat in a pan 
  • Deglaze with 30 g of white wine, then put the mussels and cockles and 10 kg of water in the pan 
  • Cook on a low heat for 3 hours 
  • Pass through a fine sieve and set aside. 

Preparing the fish stock

  • Prepare the sea bass head, discarding eyes and gills and thoroughly washing out all blood. 
  • Sauté the vegetables (300g white onion, 50g leek and 110g white mushroom)
  • Deglaze with white wine, add the fish bones and 1250 g of water and boil on a low heat for 30 minutes. 
  • Add a bunch of parsley complete with stalk. 
  • Leave to rest for 15 minutes, strain through a fine sieve and reserve. 

Preparing the base for the salsa verde

  • Roughly chop 1 kilo of onions and sauté in a pan. 
  • Deglaze with 150 g of white wine. 
  • Add the mussel stock and fish stock and cook with two bay leaves on a low heat for 1 hour, or until the desired intensity is reached. 

Preparing the salsa verde

  • In a pan, add the cold egg white and the cold salsa verde base and stir well
  • Cook on a very low heat until the white separates and rises to the surface. 
  • Clarify the salsa verde. 
  • Strain the clarified salsa verde and cool
  • Texturize clarified salsa verde at the ratio of 60g of kuzu for 1 litre of salsa 


Brown the garlic in olive oil  in a wide pan or sauté pan. Open the cockles and set aside. Next, add the salsa verdeand bring to a gentle boil. Add the sea bass, (150-200g per portion) and the peas and keep on a low heat until it is cooked (around 5 – 8 minutes). 


Put the salsa verde on the bottom of the plate and the sea bass on top.Add the peas, white asparagus, boiled egg and clams. Dust with chopped parsley.