Vichyssoise (pressure-cooker potato and leek soup, served cold)

Split the leeks lengthwise and chop into half moons, white and pale green only; chop the potatoes and the celery leaves.

Melt the butter in a 4- to 6-quart pressure cooker over medium-low heat.

Add the leeks, celery leaves and 1 teaspoon of the salt; sweat, stirring often, until soft, about 8 minutes, without browning.

Add the potatoes and the broth, bring to a simmer over medium-high heat, stirring often; lock the lid and bring to full pressure over high heat.

Once at pressure, lower the heat to medium-low to maintain it and cook 8 minutes.

Kill the heat and release the pressure by the dump valve or under cold running water.

Transfer to a blender no more than half full, working in batches, with the top of the lid open; blend on low one minute, then increase the speed slowly to puree smooth.

Return to the pot and whisk in the cream and white pepper. Taste and adjust the seasoning.

Chill the pot in a large bowl of ice water or the sink, then refrigerate at least a few hours.

Serve in chilled bowls or cups topped with a small spoonful of roe and chives. Keeps up to a week covered in the fridge, or freeze in ice cube trays up to three months.