Celeriac and Ricotta Soup with Chilli Oil and Sourdough Croutons

Soup: Melt the butter with the oil in a large saucepan and add the onion, garlic, potatoes and celeriac. Season generously, cover and cook gently for 15 minutes, stirring occasionally to prevent the vegetables from catching on the base of the pan. Add the stock, lemon zest and juice and bring to the boil. Simmer, partially covered, for 20 minutes until the potatoes and celeriac are tender.

Remove from the heat, add ricotta and blend in a food processor or with an immersion blender until smooth and creamy. Test for seasoning and if necessary add a little more salt, pepper and lemon juice.

Chilli Oil: Heat half the oil in a small saucepan over a medium heat. Add the chilli flakes and whole chilli. Cook, stirring, until the chillies start to gently sizzle for 1 minute. Add the remaining oil to the saucepan and continue to heat until the oil is warmed through. Remove from the heat and set aside to cool to room temperature. Strain into a jar and cover until ready to serve.

Sourdough Croutons: Preheat the oven to 180°C. Place the sourdough on a baking tray and drizzle generously with olive oil. Sprinkle with the sea salt and cracked black pepper and toss well to coat. Bake for 20 minutes until crisp.

To serve: Ladle the soup into bowls. Top with a drizzle of chilli oil and a generous sprinkling of croutons. Serves 4–6.