How to make: Braised cod loin, potato & mussel ragu

By Amelie Maurice-Jones

- Last updated on GMT

Great ingredients that shine: The premise of the dish reflects Wall's ethos and style
Great ingredients that shine: The premise of the dish reflects Wall's ethos and style

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Dave Wall, head chef at Britain's no.1 gastropub, the Unruly Pig, takes us through how to make braised cod loin with potato & mussel ragu, with caper, raisin and dill.

Wall has headed up the kitchen at the pub​ in Bromeswell, Suffolk, since 2015. The premise of the dish sings to his ethos and style - great ingredients allowed to shine with simplicity and clarity.

He says: "Cod is such an under-appreciated fish, but the way that beautiful loin centre-cut from large fish flakes down is one of the most beautiful textures in seafood. This method features the combination of roasting for beautiful flavour with steaming for really getting the best texture out of those flakes and I love it.

"The sauce really harnesses the wonderful briny flavour of mussels whilst lifting it to be light and fresh with the addition of the dill oil."

dave wall
Head chef: Dave Wall has been at the Unruly Pig in 2015

He goes on: "The ragu further enhances the briny umami flavour of the sea with the punchy seaweed butter and herring roe caviar complementing the mussel meat, the potatoes acting as a vessel for the intense flavours.

"The lick of brown butter hollandaise on the top could be omitted – but it further provides a layer of indulgence and I love the way it discreetly conceals the absolute flavour bomb that is hidden beneath it.

"The caper & raisin puree provides a sweet and sharp gastrique to cut through the intense umami from the rest of the dish and provide a balance."

Wall breaks down the cost of production. The prepared ballotine works out at around £25/kg, which puts a la carte portions at approximately £4.25.

Garnishes go at around £1.85 per portion, including the hollandaise, a price he puts down to the seaweed butter and herring roe caviar. Adding the cost of the sauce and caper & raisin puree takes the overall cost price to roughly £6.50. 

The chef​ recommends charging at least £25 for this dish to make a margin of around 68%.



  • 1L water
  • 60g salt

For cooking:

  • Cooking oil
  • Small knob of butter
  • 75-100ml white wine
  • A small clove of garlic, lightly crushed
  • 2 spring thyme


  • 1kg mussels
  • 250ml water
  • 250ml white wine

Mussel velouté:

  • 50g butter
  • 125g shallot, finely sliced
  • 5g garlic
  • Leaves from 5 thyme sprigs
  • 250ml mussel stock
  • 200ml double cream
  • Salt to taste

Dill oil:

  • 500ml pomace oil
  • 100g parsley
  • 200g dill
  • 6g Maldon salt

The garnish:

  • 30g blanched diced potato
  • 10g brunoise shallot
  • Pinch minced garlic
  • 10g caper
  • 8g herring roe caviar
  • 15g seaweed butter
  • Reserved mussel meat, 4 to 5 mussels
  • Squeeze lemon juice
  • Brown butter hollandaise
  • Seaweed powder

Seaweed butter:

  • 75g dehydrated seaweed
  • 500g butter unsalted
  • 250g butter salted

Brown butter hollandaise:

  • 120g egg yolk
  • 20ml white balsamic vinegar
  • ¼ tsp xanthum
  • 250g salted butter

Caper & raisin gel:

  • 1kg golden raisins
  • 250g capers
  • 250ml water

To prep


  1. Bring the water and salt to a simmer for the brine to dissolve then chill completely.
  2. Fillet cod, pin boning it and skinning it. Take care to remove the blood line.
  3. Immerse cod loin into brine and leave for 30 to 45 minutes until the flesh has firmed.
  4. Gently remove from brine, pat dry, lay two fillets together in opposing directions, had to the other tail and cling film into a tight ballotine.
  5. Allow to set into shape for at least an hour, then portion by cutting straight through the clingfilm, leaving it on to hold the shape.
  6. Portion to 165g to 170g for an a la carte portion.


  1. Clean and debeard mussels.
  2. Preheat large wide pan and steam the mussels rapidly.
  3. Cook mussels in large gastro in fridge with good circulation to cool quickly.
  4. Pick mussels delicately from shells.
  5. Strain mussel liquor through fine sieve. Store mussel meat in a little liquor. Retain remaining liquor as mussel stock.

The sauce

  1. Sweat shallots without colour in the butter.
  2. Add wine and reduce by ¾.
  3. Add mussel stock and reduce by ½.
  4. Add cream and return to gentle simmer.
  5. Blend all ingredients and pass through a fine chinois.
  6. Season to taste.

Dill oil

  1. Blend all ingredients in thermomix at 80 degrees for four minutes at speed 6 then 30 seconds at speed 10. Chill instantly over an ice bath, then allow ingredients to infuse for six to 10 hours. Hang pulp over muslin overnight to extract the oil.

The garnish

  1. Make sure potato and shallot are diced to perfection.
  2. Blanch potato for one minute in salted water and refresh.
  3. Weigh potato, shallot, garlic, caper, herring roe caviar and seaweed butter into a portioning cup ready for service.

Dehydrated seaweed powder

  1. Wash sea lettuce in five changes of cold water.
  2. Drain thoroughly.
  3. Dehydrate in a dehydrator or very low oven for 24 hours until completely dry.
  4. Blend into a fine powder.

Seaweed butter

  1. Dehydrate seaweed and blitz for powder.
  2. Blitz in blender with butter.
  3. Set in paco beaker then whip before weighing into ragu.

Brown butter hollandaise

  1. Noisette the butter, whisking consistently to ensure the solids do not burn excessively, but push it to a deep golden brown. Set in Paco beakers, chill and whip before use.
  2. Sabayon the egg and vinegar in a Thermonix speed 3/5/4 for four minutes at 80 degrees using the whipper attachment.
  3. Remove the whipper, add the xanthum, and continue blending at 80 gradually feeding the butter in as it blends. Ensure the hollandaise reaches 80 overall. You may need to feed a splash of water if it gets too thick.
  4. Decant into a cream charger siphon and charge. Hold warm.

Caper & raisin gel

  1. Bring to a gentle simmer for 10 to 15 minutes until the raisins have bloomed and softened.
  2. Blend thoroughly and pass through a fine choinois.
  3. Transfer to a squeezy bottle.

In service

  1. Preheat a frying pan over a medium-high heat.
  2. Ensure the cod fillet is proud of the cling film, then roast the cod in the oil for three to four minutes until a golden crust has formed (leaving the clingfilm on) but the fish is only around 75% cooked through.
  3. Add the butter, garlic, thyme and wine, flip the cod over and cover with a tight-fitting lid.
  4. Ensure the wine returns to the boil then remove from the stove and allow to rest for around two to three minutes in the hot braising liquor to compete the cooking.
  5. While the cod is resting, prepare the potato ragu. Preheat a small garnish pan over a medium heat.
  6. Take a spoonful of the cod pan braising liquor and add it to your potato ragu portioning cup.
  7. Add to the hot garnish pan, cooking briefly to form a glossy emulsion of the liquor and seaweed butter.
  8. When the potato is hot through, finish with the reserved mussel meat, a splash of the mussel liquor that was used to store the mussels in and lemon juice. 
  9. Put into a side dish and top with a thin layer of brown butter hollandaise and a dusting of seaweed powder. 
  10. Warm the mussel velouté to a gentle simmer, with 25g of velouté for every 5g of dill oil.
  11. Lightly whisk the velouté with the oil, taste and add a pinch of salt and a splash of white balsamic vinegar to lift it, if necessary.
  12. Gently remove the cling film from the fish, pipe a ring of the caper and raisin puree and lay the fish, browned side upwards in the centre. Sauce the plate to fill the caper puree ring. Serve with the ragu on the side 

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