Sauté aromatics - Heat the oil and melt the butter in a large heavy based pot over medium heat. Cook the onion, leek and garlic for 5 minutes until softened.
Step 2
Add the sweet potato and cumin, cook for another 3 minutes, stirring regularly.
Step 3
Simmer 20 minutes - Add the stock, salt and pepper. Bring to a simmer, then cook for 20 minutes at a gentle simmer until the sweet potato is very tender (no lid).
Step 4
Blitz - Remove the pot from the stove. Blitz with a hand-held stick until smooth. (Note 4 for blender) Stir in cream.
Step 5
Garnish - Ladle into bowls. Drizzle with yogurt, cream or olive oil with a sprinkle of something crunchy - pictured with pistachios and crispy flatbread strips (Note 3).