Step 1

Preheat oven to 220°C (425°F) / 200°C (400°F) fan. Toss potatoes in a tablespoon of extra virgin olive oil and season with salt and pepper. Arrange on a rimmed baking sheet and roast until they are browned and fork-tender, about 20 minutes.

Step 2

Meanwhile over medium heat in a large saucepan, heat 2 tablespoons of extra virgin olive oil until shimmering. Add the leeks and a generous pinch of salt. Cook, stirring occasionally, until the leeks have softened and reduced in size considerably, 5-7 minutes.

Step 3

Add the minced garlic, dill, chives and parsley and stir until incorporated. Cook until just fragrant, only about a minute or two longer. Sprinkle the flour over the leek and herb mixture and cook for another two minutes, until the raw flour smell dissipates.

Step 4

Add the cooked potatoes then pour the vegetable broth over the leek and potato mixture. Add the soy sauce, stir, and bring up to a simmer. The soup will thicken slightly but not considerably - it's meant to be relatively loose. Allow to simmer for another five minutes or so before adding the vinegar. taste to adjust for seasoning.