“Rach, I’m not convinced” said my brother earlier today as I told him about the brainwave I’d had this morning, while chugging up and down the London Fields Lido.

You see, swimming gives me real clarity of thought. It’s the perfect time to ponder serious things, such as: ‘what am I going to do with the piece of coley in the fridge?’ The brainwave came in the form of a variation on the classic B.L.T (bacon, lettuce, tomato), instead making a C.L.T (coley, lettuce tomato) for lunch.

“It’s going to need a hell of a lot of mayonnaise…” pointed out my brother, who was still playing devil’s advocate on the C.L.T. idea. Not one to let a small thing like that get in the way, I made a batch of Nathan Outlaw’s tarragon mayonnaise, and cracked on with the omega-3-rich sandwich.

It was an unmitigated success, which is why I’ve popped the recipe below. When I make it again though, I think I will attempt to introduce a bit more sharpness with a quick tomato salsa to go between the lettuce and coley, instead of the tomato slices.

A C.L.T. will, of course work with cod - or indeed catfish, carp or conger eel - but coley seemed like the most sensible and sustainable choice.

C.L.T.
Makes 1

1 tbsp olive oil
1 tbsp red wine vinegar
Salt
1/2 tomato, sliced
1 large lettuce leaf
1 fillet of coley
1 bun, halved

For the Tarragon Mayonnaise - makes enough for 4-6 buns
(Nathan Outlaw’s British Seafood)

1 egg yolk
1 tsp English mustard
4 tbsp chopped tarragon
1 tsp white wine veinegar
250ml olive oil

To make the tarragon mayonnaise, put the egg yolk, mustard, tarragon and wine vinegar into a bowl and whisk for 1 minute to combine. Slowly add the olive oil, drop by drop to begin with, then in a steady stream, whisking constantly, until the mixture is emulsified and thick. Season with a little salt.

To make the C.L.T.

Mix the olive oil and red wine vinegar with a dash of salt, and toss the tomato and lettuce in the dressing.

Rub a little olive oil and salt onto the coley skin. Put it on a tray, skin-side up, and pop under a hot grill for 2-4 minutes (depending on the size of the fillet), until it’s cooked.

On the bottom half of the bun, layer the lettuce, then the tomatoes, then the coley fillet - with a generous blob of the tarragon mayonnaise on top.