Cod’s head with sriracha butter sauce

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This is a delicious and relatively simple recipe, once you've waited for the sriracha to ferment (you need 4–6 weeks.) Utilising the fish head like this is a great way to reduce waste, it's packed full of flavour and is very cheap (if not free) from your fish mongers.

First published in 2022
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Will Murray & Jack Croft say 'This is one our signature dishes, you can either make your own Sriracha (it will keep for months in the fridge once made) or order ours from our online shop. If you can’t get Cod’s Head from your local fishmongers,we recommend the amazing team at Bethnal Green Fish Supplies. If Cod is not available, you can use other fish such as Pollock, Hake, Turbot or Brill.'




Sriracha stage 1

Sriracha stage 2

  • 10g of light brown sugar
  • 10g of tamari, or gluten-free soy sauce
  • 5g of white wine vinegar
  • 5ml of water
  • 0.02g of xanthan gum

Green oil

  • 200g of cavolo nero, grelotte tops, spring onion tops, parsley, leek tops (a mixture)
  • rapeseed oil

Butter emulsion

Cod's head


  • Hand blender



Begin by making the sriracha, as it takes 4–6 weeks to ferment. Remove the green stalk from the chillies, cut into small pieces and place into an air tight container with the garlic. Create a 2% brine by weighing how much water you need to cover the chillies, then calculating 2% of that weight and adding that amount of salt. Cover the chillies with the brine, then lay a sheet of parchment over the top and put a small plate on the top to keep it all submerged. Label the container with the date and leave to ferment for 4–6 weeks


Once fermented, transfer to a blender with the stage 2 ingredients and blend until very smooth. Pass the sauce through a fine sieve into a large pan and bring to the boil– this will stop the fermentation. Chill down the sauce overnight, then taste and adjust seasoning. Store in the fridge

  • 10g of light brown sugar
  • 10g of tamari, or gluten-free soy sauce
  • 5g of white wine vinegar
  • 5ml of water
  • 0.02g of xanthan gum

To make the green oil, blanch the greens separately until tender. It is important to take the time to blanch them separately as they have different cooking times, e.g parsley takes 5 seconds, whereas fibrous leek tops would take up to 2 minutes. Submerge in iced water to preserve colour, then squeeze out as much water as possible

  • 200g of cavolo nero, grelotte tops, spring onion tops, parsley, leek tops (a mixture)

Weigh the blanched greens, then place into a blender with double the weight in rapeseed oil. If using a thermomix, blend on speed 8 at 70ºC for 7 minutes. If using a regular blender, blitz at the highest speed for about 10 minutes. Pass through a sieve lined with a muslin cloth set over a bowl and leave to drip overnight, then transfer to a squeezy bottle

  • rapeseed oil

Preheat the oven to 180ºC/gas mark 4


For the butter emulsion, place the water into a small pan and gently heat. Gradually add the chilled, cubed butter, bit by bit, whisking to emulsify. Once all of the butter is fully melted and emulsified, blitz with a hand blender to fully incorporate


Whisk through the sriracha one spoonful at a time, until it is a light orange colour (you can adjust the heat to your preference). Keep warm and set aside


In a large pan, heat rapeseed oil until nearly smoking hot, then sear the cod’s head flesh side down. Leave to sear, pressing down on the head to achieve even colouring. Once seared, place in the oven for 5–10 minutes. Leave to rest for 5 minutes

  • 1 cod's head, cut in half
  • 2 tbsp of rapeseed oil

Dress the fish with salt, pepper and lemon juice before placing the cod’s head on a large plate and generously pour over sriracha butter sauce. Finish by splitting the sauce with a drizzle of bright green oil

First published in 2022

Jack Croft and Will Murray struck up a friendship while working at Dinner by Heston and in 2019 launched their own restaurant concept called Fallow. Together they now cook some of London’s most exciting, sustainability-focused food.

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