For the soup

• 2.5kg ripe mixed tomatoes, halved (quarter any very large ones)
• ½ bunch thyme
• 6 garlic cloves, peeled and thickly sliced
• 2 tbsp extra virgin olive oil
• Sea salt and freshly ground black pepper
• A dash of cider vinegar or a pinch of sugar (optional)

For the pesto

• 30g sunflower seeds
• 1 small garlic clove
• 75g mature Cheddar or hard goat's cheese, finely grated
• A good pinch of fine sea salt
• 1 large handful basil leaves
• 100ml extra virgin olive oil

For the mackerel

• 2 medium fresh mackerel, filleted
• 1 tbsp olive oil
• 1 bay leaf, torn
• 1 garlic clove, bashed
• 2 sprigs thyme

To serve

• Extra virgin olive oil
• A few small basil leaves
• Freshly ground black pepper

Heat the oven to 200°C (180°C fan).

Arrange the tomatoes, cut side up, in a large roasting tray in a single layer. Scatter over the thyme and sliced garlic, drizzle with the olive oil and season generously with salt and pepper.

Roast for 45 to 60 minutes, until the tomatoes are blistered around the edges and have collapsed into the tray.

Leave them to cool for a few minutes, then rub everything through a coarse sieve using the back of a ladle, pressing out as much of the rich tomato pulp as possible. Discard the skins, seeds and thyme stalks.

Pour the soup into a saucepan and bring gently to a simmer. Taste and, if needed, balance the flavour with a dash of cider vinegar or a pinch of sugar. Adjust the seasoning with salt and pepper. If you'd like a thicker soup, simmer it for a little longer.

Meanwhile, make the pesto. Toast the sunflower seeds in a dry frying pan over a medium heat for a few minutes, stirring regularly, until lightly coloured and fragrant. Leave to cool.

Place the cooled seeds in a food processor with the garlic, cheese and salt and pulse until finely chopped. Add the basil and pulse again, then gradually pour in the olive oil until you have a spoonable pesto. Taste and adjust the seasoning if needed.

When you're ready to serve, heat a frying pan over a medium-high heat. Add the olive oil, bay leaf, bashed garlic and thyme.

Cut each mackerel fillet in half to give eight pieces. Season lightly with salt and pepper and place them skin-side down in the pan. Cook for 2 to 3 minutes until almost cooked through, then turn the fish over and switch off the heat. The residual heat will finish cooking the fillets.

Ladle the hot soup into four warm bowls. Top each with two pieces of mackerel and a generous spoonful of pesto.

Finish with a drizzle of extra virgin olive oil, a twist of black pepper and a few small basil leaves.

Cook's notes

Mackerel is a rich, oily fish with wonderful flavour, but it must be very fresh. Look for fish with bright, clear eyes, firm flesh and shiny silver skin.

Sunflower seeds make a lovely alternative to pine nuts in pesto, but hazelnuts or walnuts work beautifully too.

If you'd rather use something other than mackerel, seared scallops are excellent. For a vegetarian version, caramelised wedges of fennel or lemony roasted courgettes are both delicious.

You can also simmer the soup for much longer until it reduces to a rich tomato sauce, perfect served alongside grilled fish or roasted vegetables.