Pistachio Soup with Crab

STEP 1: MAKE THE PISTACHIO SOUP
Blanch the pistachios in boiling water for 1 minute, drain, and rub off as much skin as you can to keep the soup a clean pale green. Melt the butter in a saucepan and gently sweat the leek until soft and sweet but not coloured, 6 to 8 minutes. Add the pistachios and stock, bring to a gentle simmer, and cook for 25 to 30 minutes until the pistachios are completely tender; this long, slow cook is what gives the soup its silky body. Blend until very smooth, then pass through a fine sieve. Stir in the bloomed saffron threads, lime, sour orange, cardamom and salt. Taste and balance: it should read rich but lifted by acidity. Keep warm.

STEP 2: PREPARE THE SAFFRON BEURRE BLANC
Combine the wine, vinegar, minced shallot and bloomed saffron threads in a small saucepan. Simmer until reduced to about 2 tablespoons of syrupy liquid. Add the cream and bring to a brief simmer to stabilise the emulsion. Reduce the heat to very low and whisk in the cold butter a few cubes at a time, never letting the sauce boil, until you have a glossy, pale-gold emulsion. Season with salt and a touch more acid if needed. Hold somewhere warm, not hot, so it does not split.

STEP 3: PLUMP THE BARBERRIES AND PICKLE THE SHALLOT
Barberries: rinse the dried barberries, then warm them in a small pan with the butter and sugar for 1 to 2 minutes until they plump and turn jewel-bright; do not let them scorch, as they turn bitter quickly. Pickled shallot: warm the vinegar with the sugar and a pinch of salt, pour over the sliced shallot, and leave for at least 15 minutes until soft and pink. Fennel: keep the shaved fennel in iced water until serving so it stays crisp.

STEP 4: WARM THE CRAB
Just before plating, melt the butter in a small pan over low heat. Add the Dungeness crab and warm it through very gently, only to take the chill off, 30 to 60 seconds. The crab should be barely warmed and never tightened. Fold through the lemon zest and a little salt.

STEP 5: SAFFRON RICE CRISP (OPTIONAL)
This element is optional; the plate is complete without it. If you keep it, the method below is calibrated for a light, glassy shatter rather than a dense cracker. Toss the day-old rice with the bloomed saffron threads, melted butter and salt. Spread it as a very thin, lacy single layer (the thinner the better) in a non-stick pan with the oil over medium heat. Press lightly and cook just until the underside is golden and set, about 2 to 3 minutes, stopping while it is still delicate. Slide onto paper towel; it will crisp further as it cools. Break into shards. The goal is an airy, saffron-scented crackle that flatters the soup.

STEP 6: PLATE AND SERVE
Set the warmed crab in the centre of each warm, shallow bowl and spoon a little saffron beurre blanc over and around it. Scatter the plumped barberries, a few rings of pickled shallot, and the shaved fennel around the crab. Bring the bowls and the warm pistachio soup to the table and pour the soup tableside, so it meets the garnishes at the moment of serving. Finish, if using, with a shard or two of the saffron rice crisp and a few reserved chopped pistachios.