In the summer, I adore a one-pot-dish that’s full of vegetables: Less washing up, a light flavour, and no long cooking times heating up our flat. This particular dish was inspired by the idea of petits pois a l’ancienne (braised lettuce with peas) which is a classic French dish often served with robust flavours like pigeon. For a brilliant example of how it is done classically, here’s one of my favourite food porn videos. I wanted a lighter version that would be perfect to serve with a delicately poached fillet of white fish – in this case cod. The end result was a super, light weeknight meal with the sweetness of leeks, saltiness of bacon, and an occasional burst of intensity from mustard seeds all paired with the gentle bitterness of braised lettuce and delicious, flaky, unctuous fish. Not to mention, unlike some other fish recipes, the cooking of the cod couldn’t be easier…
The base of the dish is made of sweet, slow cooked leeks. Like most members of the allium family, leeks are full of natural sugars. So, after some gentle cooking, they become beautifully sweet whilst staying savoury – just like my favourite caramelised onions. Unlike in that recipe, leeks can take a slightly higher heat because they are naturally sweeter than onions, so you can cook them a little faster – a great boon for a quick midweek meal. This will give a sweet back bone to the dish that will infuse the fish stock used to braise the gem lettuces. However, as well as sweetness, we want some other more robust, savoury flavours as well.
To build up those savoury notes, we start by blooming some mustard seeds in olive oil. Blooming spices in oil is very common in Indian cooking, as it both adds a toasted note to the spices themselves and draws the flavour of the spices out into the oil, which then mingles throughout the dish. We then add cubes of pancetta and cook until lightly browned, which adds a deep salty and savoury note to the dish. This base of mustard seeds, bacon, and the slow cooked leeks can be done as far in advance as you like, meaning the final dish can come together in under ten minutes! However, there are still a few more flavours we need to incorporate. Good fish stock is essential to build the layers of flavour. It’s fairly easy to find in the UK (stock cubes don’t count!) but, if you can’t find it in your local, it’s very easy to make. Simply take some fish bones – most fish counters will give you these for free – a little fennel and fresh herbs and simmer gently in some water for around 30 minutes. Finally, it’s important to incorporate some aromatics. I like to add quite a lot of black pepper (and occasionally some cayenne for real heat) because I think it pairs well with the sweeter elements of the dish. As well as pepper for warmth, the dish is lifted by the addition of some fresh tarragon. Its gentle aniseed note is a classic combination with fish for a good reason – I personally can’t stand aniseed in general, but I still find tarragon irresistible in this dish.
Cooking the fish itself is remarkably easy. The only two challenges are stopping the cod from falling apart and not overcooking it. In order to both intensify the flavour and firm up the flesh of the cod, I salt it for around 10-30 minutes before cooking. Then, after you have washed the cod to remove the excess salt, it is notably firmer and the water has leached out making it taste both more intense and more subtle. This will also help to stop it from falling apart and is a great tip, not just for this dish but really any time you’re cooking a flaky, white fleshed fish like cod. The cooking itself will take no more than 5 minutes – often less. I place it on top of the simmering liquid and cover with a pan lid. Cook for around 1-2 minutes before flipping, recovering and cooking for another 1-2 minutes depending on the thickness of the fillet. Just make sure the liquid isn’t boiling aggressively. If you are especially worried about the cod falling apart, it can help greatly to cover each fillet on both sides with a little greaseproof paper. This makes flipping the fish easier, but isn’t strictly necessary.
I hope you like this dish as much as I do – it’s become a firm staple in our house over the warmer months when you still want a hot dinner but you want it to be light, summery and intensely moreish. You can play with the spices, the fish choice and the vegetables – peas are a classic choice which I almost added to this recipe. You could try increasing the heat with some espelette or cayenne pepper, or even some chilli flakes. Maybe try some light curried flavours in the leeks, or finish the dish with an intense chive oil. Just remember to try to keep a balance between the salty, sweet and aromatic flavours and to cook the fish gently, then you’ll be onto a winner.
Cod with braised lettuce, mustard seeds and tarragon
- 4 Cod fillets
- 3 Leeks – quartered lengthwise and then finely sliced
- 250ml fish stock (You might need a bit more depending on the heat and depth of the pan
- 150g bacon
- 120g cooked crayfish tails (could also be prawns or small queen scallops)
- 4 baby gem lettuce quartered lengthwise with some of the root removed
- 1 tablespoon yellow mustard seeds
- 15 or so tarragon leaves very finely chopped
- Small knob of butter
- Salt the fish fillets very thoroughly. You will wash this salt off so don’t worry about over salting. Cover and refrigerate for 15-30 minutes and then wash the salt off thoroughly.
- Heat a glug of olive oil in a frying pan over a medium heat and add the pancetta. Cook until cooked through but not browned. Add the mustard seeds and fry for a further minute.
- Add the leeks and a generous helping of black pepper and cook over medium heat for 15 minutes until softened but not browned.
- Add the quarters of gem lettuce in one layer, cover with fish stock and bring to the boil over a high heat before turning down to a simmer, cook for a minute or two.
- Lay the fish fillets on top and cover the pan with a lid. Cook for 90 seconds. Flip the fish, recover and cook for another 90 seconds.
- Remove the fish and set aside. Add the tarragon, butter and cooked crayfish (if using raw shellfish then add for last 90 seconds of fish cooking time). Stir and reduce the liquid slightly, adjust seasoning with salt and black pepper.
- Ladle some of the vegetables and broth into bowls and add a piece of cod to each bowl
TimedEating tips and tricks for cooking cod with braised lettuce ahead of time
- The leeks and bacon mixture can be cooked up to week in advance. That means you can make it when you have time and then it will take less than ten minutes to finish dinner when you want it.
- Otherwise, there’s not a lot to do ahead except make sure to prep all your vegetables in advance. In a restaurant all the vegetables would be chopped, the leek and bacon mixture would be made and it would be order to plate in 10 minutes.