SPHERIFICATION OF OYSTER SOUP

A part of our Kitchen Theory ‘Elements’ multi sensory dining events we are using the reverse spherification process as a main element on our ‘Sea Spheres’ dish. (note: this event has ended, please view our upcoming events.) This is one of my favorite dishes; its conception was very much driven by the desire to use the spherification process in a manner which made sense and a format which would be delicious. During the initial phase of developing the ‘Elements’ menu we wanted to use spherification as part of our ‘waster courses’ but were put off by how over used the technique has become as a part of modernist cooking. So we began by looking at examples of sea food related dishes which we believed could be further enhanced by spherification and add to the dishes over all result rather than detract from it. After many different directions were taken I stumbled across the idea of using oysters; what better way to encapsulate the freshness and flavour of the sea?  From this point onward we began to develop a concept for the dish which rather than destroy the oyster and over power its natural flavours, would enhance the oysters textural and flavour properties. The resulting sphere of oyster infused dashi is served with a variety of seaweeds all relating to the oysters natural habitat (and heightening the umami content) as well as red currents and gooseberries (while they were in season) to provide the sharp acidic contrast to the umami rich seaweed and creamy oyster. Now all this could have been nicely presented on a slick Japanese spoon, but as part of our original premis to keep the oyster’s identity and connection to the sea and nature we served the dish in oyster shells (which we pasteurized) on ice. The recipe for our ‘Sea Spheres’ is as follows: Ingredients (Serves 10+):

• 4 Fresh oysters
• 1Ltr Dashi (japanese seaweed and katsobushi stock)
• 50ml Kikoman soy sauce
• 1Ltr Deionised water
• 5g Sodium Alginate (we use ‘Algin’ product by Texturas)
• 10g Calcium gluconate (we use ‘Gluco’ product by Texturas)

Equipment:

• Medium sized demi-sphere silicon moulds
• Freezer
• Plastic containers for the water bath

Method: Part 1: The oyster spheres

• Shuck the oyster (reserving and straining their natural juices and wash gently with 500ml of the dashi)
• Strain and reserve the dashi used to clean the oysters
• Combine the oyster, oyster juice, and dashi (the 500ml used to wash them)
• Leave to marinate overnight (we vacuum pack the ingredients together for maximum diffusion of flavours)
• Once the oyster soup is marinated, strain and reserve the liquid and oysters separately
• Add the soy sauce to the oyster soup and mix well
• Add the calcium gluconate and whisk till completely dissolved
• Cut the oysters into small pieces and place into the demi-sphere moulds
• Pour in the oyster soup over the oysters in the moulds and carefully place in the freezer till the spheres are frozen solid.

Part 2: Sodium Alginate bath

• Pour the water into a container and add the sodium alginate
• Blend the water and sodium alginate together using a hand held stick blender. This process may take up to 5 minutes in order to make sure the sodium alginate is completely dispersed.
• Leave the alginate bath on the side for at least an hour so that the air bubbles incorporated by the hand held blender can escape (we use a vacuum packing machine as it speeds up the process by removing all the air bubbles instantly)

Part 3: Finishing the Spheres

• Place the sodium alginate water (which should look like clear water, just more viscous) in a plastic container(s) so that it forms a water bath roughly 3 inches deep. Make surethe solution is at room temperature.
  

  Oyster shperes in the Alginate bath

• Remove the frozen spheres from the freezer and de-mould then one by one placing them in the alginate bath (make sure they do not touch each other, as they will stick together!)
• Leave the spheres in the alginate bath for around 4 to 6 minutes making sure to move them around  and flip them gentlyso that they form a uniform gel coating all around.
• Once the spheres are ready remove them from the alginate bath and place then into a similar water bath which is just regular clean water for around 30 seconds (this is just to clean off any excess calcium/alginate)
• Then place the spheres in the remaining 500ml of dashi (this is to continue marinating the spheres until you are ready to serve).

For serving suggestions please see our presentation for the ‘Elements’ pop up event. The spheres are served with a variety of seaweed including wakame, hajiki, tosaka, as well as seaweed caviar (a Swedish product I stumbled across) and red currant. If you have any questions regarding any of the dishes from one of our events please contact us for a recipe, techniques or further  information)