Ingredients

• 2 large free-range egg yolks
• 1 tbsp white wine vinegar
• 2 tsp Dijon mustard
• ½ tsp caster sugar
• ¼ tsp flaked sea salt
• freshly ground black pepper
• 150ml/5fl oz sunflower oil
• 100ml/3½fl oz crème fraîche
• 65g/2¼oz shelled walnut halves
• 3 large sticks of celery
• plus celery leaves
• 2 eating apples
• quartered and finely sliced
• 250g/9oz seedless red grapes
• halved
• around 2 tsp fresh lemon juice
• 8 fresh mackerel fillets
• 4 tsp olive oil
• 4 tsp lemon juice
• 2 tbsp flatleaf parsley
• finely chopped
• flaked sea salt and freshly ground black pepper

Directions

• To make the mayonnaise put the egg yolks
• vinegar
• mustard and sugar into the small bowl of a food processor
• or if you don’t have a food processor with a small bowl
• you can use a stick blender. Season with salt and some ground black pepper.
• Blend until smooth
• then with the motor running
• gradually add the oil and blend until smooth and thick. Add the crème fraîche and 1-2 tablespoons of cold water. Blend for a few seconds more until the sauce has a soft dropping consistency. Transfer to a bowl
• cover and chill in the fridge.
• For the salad
• place the walnut halves into small non-stick frying pan over a medium-high heat for 3-4 minutes
• or until toasted all over. Leave to cool. Finely slice the celery
• keeping the leaves for later. Add the sliced celery to a large bowl together with the sliced apples and halved grapes. Pour over the lemon juice and toss well. This will keep the apples from going brown. Mix in the mayonnaise
• toasted walnut halves and celery leaves.
• Preheat the grill to the highest temperature setting. Add the mackerel fillets to a large mixing bowl and pour over olive oil and lemon juice. Sprinkle over the parsley and season with flaked sea salt and freshly ground black pepper. Toss well
• ensuring the fillets are well coated. Transfer the mackerel to a baking tray
• skin-side up
• and grill for 2-3 minutes
• or until the skin is crisp. Serve the mackerel fillets immediately
• with the Waldorf salad and a wedge of lemon.