Ilove ketchups. I love how their tart sweetness makes my mouth water, and how you can preserve a whole gamut of fruits by cooking them down with onion and spicing in this sweet-sour celebration. The barely-there scent of cucumber in today’s ketchup works wonderfully with fish; I like to highlight the lightness of both with a herb-flecked barley salad peppered with the sweet crunch of apple and toasted seeds. A summery dish that smacks of seaside holidays, and perfect for the forthcoming jubilee celebrations. Grilled mackerel with herbed pearl barley salad and cucumber ketchup The smokiness that comes from grilling the mackerel works beautifully with the sharpness of the ketchup. You can also roast the fish instead, if you prefer. Prep 10 min Cook 50 min Serves 4 125g pearl barley, rinsed 30g sunflower seeds 3 tbsp extra-virgin olive oil, plus extra to grease the fish Juice of ½ lemon Salt and pepper 2-4 mackerel (depending on their size), gutted and cleaned 70g rocket 2 apples, quartered, cored and sliced 40g mix of mint, chervil, parsley and dill, roughly chopped For the ketchup ​​2 cucumbers, cut into large pieces 1 small onion, peeled A small thumb of ginger, peeled 2 large garlic cloves, peeled 1 tsp dijon mustard 80ml sherry vinegar 2 tbsp caster sugar First make the ketchup. Put everything in a blender, puree until smooth, then pour into a large saucepan and bring to a simmer. When the mix starts to bubble, turn down the heat to medium-low and cook, stirring occasionally, for 35-40 minutes, until reduced by a third. Meanwhile, bring a pan of salted water to a boil, then simmer the pearl barley according to the packet instructions (usually 25-30 minutes), until tender. While the barley is cooking, toast the sunflower seeds in a dry pan until lightly browned, then tip into a small bowl. Once the pearl barley is cooked, drain and empty into a separate bowl, dress with the olive oil and lemon juice, and season. Heat the grill to its highest setting. Season the mackerel and rub all over with a little oil. Grill for three to four minutes on one side, then turn over and grill for a few minutes more on the other side, until a skewer slides easily into the thickest part of the fish with no resistance. Toss the barley with the remaining salad ingredients, setting aside some of the herb mix to garnish, and pile on to plates with the mackerel and spoonfuls of cucumber ketchup. Scatter with the extra herbs and serve. The simple flex Cut aubergines into long slices and chargrill or barbecue – they’re delicious served with this salad and ketchup. UK readers: click to buy these ingredients from Ocado The Guardian aims to publish recipes for sustainable fish. For ratings in your region, check: UK; Australia; US.