Grilled mackerel, beetroot and red onion salad

1. Put the beetroots in a large pan. Cover with water and boil for 45-50 minutes, or until soft – a cutlery knife should pierce them easily.

2. Meanwhile, put the onion in a bowl with the salt, sugar and vinegar and mix well; set aside to marinate. Toast the cumin and coriander seeds in a small frying pan until fragrant, then crush in a pestle and mortar (or spice grinder). Stir 1 tbsp oil and the zest of ½ lemon into the crème fraîche; season.

3. Drain the beetroots, then rub the skins off while still hot using clean rubber gloves or a clean, old tea towel (it will stain). Dice into roughly 1cm cubes, then toss with the pickled onions, crushed seeds and herbs, 2 tbsp oil and remaining zest of ½ lemon; season.

4. Preheat the grill to high. Season the mackerel on both sides, place skin-side up on a baking tray and drizzle with the remaining ½ tbsp oil. Put under the hot grill, and cook until the skin is golden and the flesh cooked through, about 2-3 minutes. Divide the salad between 4 plates, along with a little crème fraîche. Sit a mackerel fillet on top and serve with more crème fraîche, extra dill and lemon wedges to squeeze over.