Preheat the grill to full blast. First, make the dressing. Strip the leaves from the rosemary (you should be left with roughly a teaspoonful) and put in a blender with the egg yolks, garlic, mustard, vinegar and lemon juice. Blend until well combined, then slowly, in a thin dribble, add the oil. If the dressing appears too thick, add a splash of hot water and blend until the dressing reaches a double cream-like pouring consistency. Leave to one side while the other ingredients are prepared.
Place the mackerel, seasoned and lightly oiled, on a foil-lined grill tray. Grill for four to five minutes on each side until cooked. Allow to cool.
Cook the potatoes in a large saucepan of simmering water for about 15 minutes until tender, adding the beans for the last five minutes of cooking time. Drain in a colander, then immediately plunge into a bowl of iced water and leave to cool completely.
Lower the eggs gently into another saucepan of boiling water. Return to the boil and cook for eight minutes. Cool quickly under running water until cold. Peel the eggs and cut in half. They should be only just hard-boiled, with the yolk moist and a rich golden-yellow colour.
Remove and discard the mackerel skin and take the flesh from the bones in nice large flakes, being careful to remove bones.
Drain the potatoes and cut into fairly thick slices. Cut the anchovies in half lengthways and the tomatoes through the middle. Roughly tear the lettuce leaves. Toss the mackerel pieces, potatoes, green beans, lettuce, anchovies, tomatoes, olives, capers and basil leaves loosely together in a large salad bowl. Put the halved eggs here and there before liberally spooning over the dressing. Eat with a cold bottle of rosé.
2 large mackerel, gutted and degilled
flaked sea salt and ground black pepper
1 tablespoon light olive oil.
350g waxy new potatoes, eg Charlotte or Jerseys, well scrubbed
125g fine green beans, stalks trimmed
4 small free-range eggs (at room temperature)
8 good salted anchovy fillets in oil, drained
100g vine cherry tomatoes
1-2 Baby Gem lettuce
a handful of good black olives in oil
2 tablespoons baby capers, drained
a handful of small fresh basil leaves
For the dressing:
half a short stalk of rosemary
2 small free-range egg yolks
2 garlic cloves, peeled and roughly chopped
1 teaspoon Dijon mustard
1 tablespoon red wine vinegar
1 tablespoon freshly squeezed lemon juice
100ml light olive oil
From 'What To Eat Now – More Please' by Valentine Warner (Mitchell Beazley, £20) Picture by Howard Sooley