Knobbly and rough, celeriac is tastier, sweeter, better textured and more interesting than its humble looks would ever lead you to believe. You'll find it at farmers' markets until the very end of the season because it is both frost tolerant and easy to transport, demanding nothing except to be taken home and given a chance to impress. You can cut celeriac (a.k.a. celery root) up into cubes and roast it or add it into your mashed potatoes for a surprising jolt of flavour, but it is most delicious when it's puréed into a soup, with a bit of apple to both highlight its sweetness and play against its savoury celery-ness. Walnut oil gives an interesting final flourish.
Ready time: 45 minutes
1 tablespoon olive oil
1 onion, finely diced
1 carrot, finely diced
1 large celeriac, peeled and cut into 1-inch pieces
2 MacIntosh apples, peeled and cored
2 cups chicken or vegetable stock
2 cups water
1 teaspoon salt
Freshly ground pepper, to taste
½ cup light cream
Walnut oil, to taste
1 tablespoon snipped chives
Heat olive oil over medium in a large saucepan. Add onion and carrot and sweat until fragrant but not brown, 1 to 2 minutes. Add celeriac and sauté until lightly browned, 3 to 5 minutes. Cut apples into chunks and add to pan, along with stock and water. Simmer over low heat until celeriac and apples are soft, about 20 minutes. Purée with an immersion blender. Season with salt and pepper. Stir in cream over low and heat soup through but take care to avoid boiling.
Ladle soup into bowls and garnish with a drizzle of walnut oil and a few snipped chives.