Vanilla poached plums, cardamom custard & hazelnut-sumac crumble

1. Put the milk in a pan and add the crushed cardamom seeds. Bring to a gentle simmer, then take off the heat. Set aside for 30 minutes to infuse. Meanwhile, make a vanilla poaching liquor: split the vanilla pod in half, scrape out the seeds and put both seeds and pod in a large pan, along with 150g sugar and 1 litre of water; stir and bring to the boil. Turn down the heat and simmer for 10 minutes, until reduced a little.

2. While the liquor is cooking, halve the plums and remove the stones. When the liquor is ready, add the fruit and simmer over a low heat for about 5 minutes, until just cooked (you may need to do this in batches). Remove with a slotted spoon and transfer to a plate. Discard the leftover liquor.

3. To make the custard, whisk the eggs, the remaining 100g sugar and the flour together in a bowl. Bring the infused milk back to a simmer, then strain it through a sieve into the egg mix, stirring continuously. Return this mixture to the pan and cook over a low heat, whisking continuously until the custard becomes very thick and leaves a trail when the whisk is lifted; this will take about 10 minutes. Cover the surface of the custard directly with baking parchment, to stop a skin forming, and put the pan into a bowl of iced water to cool.

4. Meanwhile, preheat the oven to 180˚C, gas mark 4. For the crumble, mix the flour and sugar in a bowl, then rub in the butter with your fingertips until it resembles breadcrumbs. Stir in the nuts and spread the mixture out on a baking sheet. Bake for 15-20 minutes, stirring halfway through, until golden brown. Allow to cool to room temperature, then stir in the sumac and salt. To serve, put a dollop of the custard in a bowl, top with fruit and finish with a scattering of crumble.