Preheat the oven to 400°F fan.

Make the fenugreek onions by starting with the spice mix. Add the fenugreek, coriander, cumin and cardamom seeds to a small frying pan and toast on a medium-high heat for 3 minutes or until fragrant. Remove from the heat and add the turmeric, then transfer to a spice grinder and blitz until smooth. Measure out 1 teaspoon and set both aside while you cook the onions.

Put 3 tablespoons of the oil and 1½ tablespoons of the butter into a large frying pan on a medium-high heat. Once the butter has melted, add the onions and ½ teaspoon of salt, then turn the heat down to medium and cook for 20 minutes, stirring occasionally, until softened and lightly golden. Add the chile and cook for another 2 minutes, then add the larger amount of spice mix and 2 teaspoons of the sugar, stir for 30 seconds, then remove from the heat.

Put the remaining 3 tablespoons of oil, 3 tablesppons of the butter, the remaining ¼ teaspoon of sugar, 1 teaspoon of spice mix and ¼ teaspoon of salt into a 12 x 8-inch/30 x 20cm baking dish and mix together (don’t worry about the butter not being melted). Season the fish fillets all over with ⅓ teaspoon of salt and a good grind of pepper. Top each fillet with the onion mixture in an even layer, then gently transfer to the baking dish. Dot the top of the fish with the remaining 1½ tablespoons of butter. Roast for 15 minutes, or until just cooked through (roast for less time if your fillets are smaller). Spoon over the tablespoon of lemon juice. Gently transfer the fillets to a serving platter and pour over the butter mixture.

Meanwhile, prepare the peas. Put the cilantro, mint, garlic, chilli, yoghurt, lemon juice, 1 tablespoon of the oil, ¼ teaspoon of salt and a good grind of pepper into the small bowl of a food processor and blitz until smooth, scraping down the sides of the bowl as needed. Put the peas, broad beans, the remaining 2 tablespoons of oil and ½ teaspoon of salt into a medium saucepan and place it on a medium-high heat. Cook, stirring occasionally, for 3–4 minutes, just to heat through without losing their colour. Off the heat, stir in the herby yoghurt and transfer the peas to a serving bowl. Serve this alongside the hake, with the lemon wedges to squeeze over.