- For the Fennel Purée, remove and reserve green tops of the fennel. Trim the base of the fennel and remove the outer layers, reserving the inner bulb.
- Place a medium saucepan of water over high heat. Stack the fennel layers in a boilable vacuum seal bag and vacuum seal. Boil the vacuum sealed fennel until completely soft, about 30 minutes.
- Place the wine into a saucepan and bring to a simmer until reduced to ¼ of its original volume. Remove from the heat and set aside.
- Once fennel has cooked, transfer contents of the bag to the canister of a stick blender. Add the butter and blend to a smooth purée, adding a little water if necessary. Pass through a fine mesh sieve and season with salt and some reduced white wine. Place purée in a squeeze bottle and set aside.
- For the Onion Slivers, bring a saucepan of liberally salted water to the boil. Slice the onions in half lengthwise and discard skins. Carefully remove the 2 outermost layers of the onion halves in one piece, without damaging them. Blanch in the boiling water for 6-8 minutes then refresh in iced water. The onion shells should be sweet with no raw taste, but still crunchy. Slice the onion layers lengthwise into 5mm wide slivers and reserve for assembly. Dice remaining onion into 5mm dice and reserve half for the Fumet, and half for the Filling.
- For the Crayfish Fumet, place the oil and crayfish shells into a large pan over medium high heat. Sauté shells for 15 minutes until well browned. Add onions, mustard and ovaries and continue to simmer until onions are soft and translucent, about 10 minutes. Add the crayfish head and use a potato masher or mallet to break down shells and head into small pieces. Cover with water. Bring to a boil and simmer until reduced by half. Remove from the heat and pass through a fine mesh sieve and discard solids. Return the liquid to the pan and simmer until reduced by half. Pass through a fine mesh sieve lined with muslin cloth and season with reduced white wine.
- For the Crayfish Filling, chop the reserved fennel into a 5mm diced place in a small bowl. Sprinkle generously with salt and toss to combine, then add enough water to the bowl to just cover the fennel. Allow to brine for 50 minutes then drain through a sieve.
- Meanwhile, in a pan over medium heat, add the diced onion with a little grapeseed oil and sauté for about 15 minutes until soft and lightly browned. Remove from the heat and set aside to combine with filling.
- Bring a saucepan of heavily salted water to a boil. Place crayfish meat in a small fine sieve. Once the water reaches a boil, remove from heat then carefully submerge the sieve of crayfish meat into the water to poach for 1-2 minutes. Check the meat during this process and remove the small pieces once they are just cooked, returning the larger pieces to the water until done. Chop the cooked crayfish to a 5mm dice and place in a bowl.
- Weigh the crayfish meat and add half that weight of drained diced fennel and sautéed onion. Combine mixture and taste, adding more of the fennel and onion if desired, but ensuring crayfish is the dominant flavour. Season the mixture with lemon juice.
- To assemble, pipe three 2cm dots of the fennel purée onto each serving plate. Place a heaped tablespoon of the crayfish filling on top of the fennel purée in a neat pile. Dot the top of each pile with more of the fennel purée. Carefully cover the piles of crayfish filling with the onion slivers and arrange so the piles now resemble small onions that have been cut in half. Finally, carefully add some fennel fronds by slightly wedging them between the onion slivers.
- To serve, pour the crayfish fumet into the centre of each plate, stopping when the fumet surrounds half of each of the ‘onions’.
*this recipe uses all but the tail portion of a whole crayfish. Separate the head from the tail and trim the tail flush with the edge of the shell. The trimmings can be used in recipe as above and the intact tail can be used for another recipe.