Chilled tomato soup with grilled mackerel

Method

1. Using a sharp knife, score a small cross on the base of each tomato. Put in a heatproof bowl and cover with freshly boiled water. Leave for 15 seconds, then drain and refresh in cold water. Peel off the skins (they should come away easily). Cut the tomatoes in half, squeeze out and discard the seeds, then chop roughly.
2. Put the tomato flesh into a blender or processor with the orange juice, coriander seeds and tomato purée. Season with salt and pepper, whizz until smooth, then press through a sieve using a wooden spoon or ladle.
3. Add 1 tbsp sherry vinegar, then taste and adjust the seasoning as needed – you may need a splash more sherry vinegar. Chill for at least 3 hours (see make ahead). The air bubbles will leave the soup and the colour will intensify to a deep red.
4. When the soup has chilled, peel the cucumber, halve lengthways, then remove the seeds with a teaspoon. Cut the cucumber halves into 4cm lengths, then into batons. Season with salt, pepper, extra-virgin olive oil and lemon juice, then toss to combine.
5. Heat the grill to high. Run your fingers over the cut-side of the mackerel fillets to locate any pin bones, remove using fish tweezers (see tip), then wash and pat dry. Cut each fillet diagonally to give 2 roughly diamond-shaped pieces, brush with a little oil and season with salt and pepper. Grill, skin-side up, for 2 minutes, then cook for 1 minute on the other side.
6. Divide the cucumber evenly among 6 soup plates, piling it up in the centre. Top each pile with a piece of hot mackerel, pour the cold tomato soup around, then garnish with fresh basil leaves and a drop or two of olive oil.