Persian Saffron Rice with a Golden Crust and Barberries

Rinse and soak the rice. Rinse the basmati in the bowl, swirling and changing the water 5-6 times until it runs clear, then cover with fresh cold water and leave to soak for 30 minutes, or up to 2 hours. Drain well afterwards. Soaking hydrates the grains evenly so they lengthen and cook through at the same rate once they hit the pot.

Steep the saffron. Grind the saffron threads to a fine powder in the mortar, then tip it into the small bowl and steep in the 3 tbsp hot water. Crushing the threads first breaks them open so the colour and aroma release fully into the water rather than staying locked inside the strands.

Parboil the rice. Bring the 2.5 litres of water to a rolling boil with the salt, then add the rice, stir gently and boil for 5-7 minutes. You're looking for grains that have lengthened and are soft on the outside but still have a firm core when you press one between your fingers. Drain in the sieve and rinse under cold water for 30 seconds, which stops the cooking instantly so the rice doesn't turn mushy before it even reaches the pot.

Mix the crust layer. In a bowl, combine 200g of the parboiled rice with the yoghurt, egg yolk and half the saffron water. The yoghurt and egg yolk set against the hot pan to form the crisp, golden crust, so this mixture needs to be worked through evenly before it goes anywhere near the heat.

Line the pot. Heat the oil and 30g butter in the non-stick pot over medium heat until the butter foams, then spread the yoghurt rice mixture in an even, pressed layer across the base. Pressing it down firmly now is what gives you a solid, unbroken crust later rather than one that breaks apart on turning out.

Mound the remaining rice. Spoon the rest of the rice on top, shaping it into a mound that doesn't touch the sides of the pot, then poke 6-8 holes down to the base with the handle of the spoon. These holes give the steam a route up through the mound so every grain cooks evenly rather than just the rice nearest the heat.

Sizzle uncovered. Cook uncovered over medium-high heat for 8-10 minutes, until you can hear a steady sizzle and see oil bubbling gently at the edges of the pot. This is the point where the base crust starts to form, so resist the urge to cover it too soon.

Steam under a wrapped lid. Drizzle the butter-water over the mound, then wrap the lid in the tea towel, tying the corners up over the handle and keeping the fabric well away from the flame, and cover the pot tightly. Turn the heat to low and cook for 45-50 minutes, giving the pot a quarter turn every 10-12 minutes so the crust browns evenly rather than just on one side. The towel absorbs the rising steam instead of letting it drip back onto the rice, which is what keeps the top light and fluffy while the base at the bottom turns deep golden; the yoghurt-and-egg crust will comfortably reach well above the 71°C it needs to be fully set.

Glaze the barberries. Melt the 10g butter in the small frying pan over low heat, add the barberries and sugar and stir for 1 minute until glossy, watching them closely as they burn in seconds. Take them off the heat the moment they look shiny.

Rest, then turn out. Set the pot on a damp tea towel for 3-4 minutes; the sudden temperature change helps the crust let go of the base. Run a spatula around the edge, place the serving plate over the pot and, holding both firmly with oven gloves, flip the whole thing over in one confident movement before lifting the pot away. Drizzle over the remaining saffron water, scatter with the glazed barberries and cut into wedges so everyone gets a piece of the crust.