To begin, make the pickled rhubarb. Place the water, sugar, white wine vinegar, lemon juice, vanilla and salt in a pan and bring to the boil, stirring until the sugar has dissolved. Add the rhubarb and cover with a cartouche, reducing to a simmer
30g of white wine vinegar
200g of rhubarb
35ml of water
30g of caster sugar
1 lemon, juiced
1/2 tsp vanilla paste
1 pinch of salt
2
As soon as the rhubarb is barely cooked and still firm, remove from the heat and allow to cool in the pickling liquid – ideally for 12 hours but less if you’re short on time
3
For the rhubarb sauce, melt the butter in a pan over a low to medium heat. Add the sugar and vanilla paste and slowly cook until the rhubarb is completely soft, most of the moisture has evaporated from the pan and the mixture is thick. Blend in a high-powered blender, pass through a fine strainer and set aside
20g of butter
1 tbsp of caster sugar
150g of rhubarb, finely and evenly sliced
1/4 tsp vanilla paste
4
Let the sauce down with a dash of the rhubarb pickling liquor and add some white wine vinegar to taste. Season with salt and pepper
white wine vinegar, to taste
black pepper
salt
5
To cook the fish, brush the flesh of the mackerel with English mustard using a pastry brush or the back of a spoon, and season with salt and pepper. Heat some olive oil in a non-stick pan and add the fillets skin-side down, pressing down evenly for 30 seconds with a spatula to ensure an even colour
olive oil, for pan-frying
4 mackerel fillets, each weighing 100–120g
1 tbsp of English mustard
salt
pepper
6
Leave to cook on this side for 2–3 minutes depending on the thickness of the fillets, then turn the fish over and remove from the heat. It will finish cooking in the residual heat of the pan
7
To make the vinaigrette, place the mustard in a bowl, whisk in the white wine and water, then drizzle in the olive oil. Season with salt and pepper and emulsify using a hand blender or whisk
salt
1 tsp wholegrain mustard
50g of white wine vinegar
50g of water
200g of extra virgin olive oil
pepper
8
To serve, dress the salad leaves with a little vinaigrette and squeeze some fresh lemon juice over the mackerel. Place some of the rhubarb sauce on the plate and top with some pickled rhubarb and a mackerel fillet. Garnish with salad leaves and some of the mustard vinaigrette