Sweet potato soup: roasted, not boiled, and you can taste it
Sweet potatoes boiled in water give a soup that is one-dimensionally sweet and slightly watery. The same sweet potatoes roasted in the oven lose some water and caramelise at the edges — the soup then becomes deeper, darker and clearly more complex. It costs about forty minutes during which the oven does the work. The rest is ginger, curry and coconut milk to balance the sweetness.
Your own work in that: 8 min.
- Roasting (make the base meanwhile) 40 min
- Simmering with stock 12 min
- Blending and serving 8 min
Step by step
0 / 5 doneRoast the sweet potatoes in their skins
Heat the oven to 200 °C. Halve the sweet potatoes lengthwise, drizzle with oil, salt them and lay them cut side down on the tray. Roast for 35–40 minutes, until completely soft (a knife slides in without resistance) and darkly caramelised where they meet the tray. That caramelisation is what gives the soup its depth.
Ingredients: 1000 g sweet potatoes · 2 tbsp olive oil · ½ tsp salt
TipCut side down, not up: the steam is trapped, they cook faster, and the contact surface caramelises as it would in a frying pan.
Cut side down, edges darkly caramelisedFry the aromatic base
During the last 10 minutes of roasting, melt the butter in a pot and cook the chopped onion for 6 minutes, add the garlic and grated ginger for a minute, then the curry powder and chilli and fry another 60 seconds, stirring constantly. Spices bloomed in fat give a completely different aroma from spices stirred into liquid later.
Ingredients: 1 pcs onion · 3 cloves garlic · 25 g fresh ginger · 2 tsp curry powder · ½ tsp chilli flakes · 20 g butter · 700 ml vegetable stock · 400 ml coconut milk · 1 pcs lime, juice · 1 tsp salt
TipThis is called tempering the spices, and it needs watching: curry powder burns quickly, and burnt it turns bitter and ruins the soup beyond repair.
Spices in fat, one minute, constant stirringScoop the flesh and add stock
Scoop the flesh out of the skins straight into the pot (discard the skins). Add the stock, bring to the boil (about 2 minutes) and simmer 10 minutes so the flavours come together. The soup will be very thick, which is normal — the coconut milk loosens it.
Blend and add coconut
Blend completely smooth, about 2 minutes. Pour in the coconut milk, keeping back two tablespoons for the garnish, and warm through for 2–3 minutes without boiling. Season with salt and the juice of a whole lime — without acid this soup is simply sweet.
Ingredients: 1 pcs onion · 3 cloves garlic · 25 g fresh ginger · 2 tsp curry powder · ½ tsp chilli flakes · 20 g butter · 700 ml vegetable stock · 400 ml coconut milk · 1 pcs lime, juice · 1 tsp salt
TipShake the tin of coconut milk before opening, or stir its contents together. The fat sets at the top and poured in separately it leaves white lumps in the soup.
A whole lime, or the soup is only sweetServe with seeds and coriander
Ladle into bowls, add a teaspoon of coconut milk to each and drag a skewer through it into a spiral. Scatter with toasted pumpkin seeds and coriander. The seeds are the only crunch in an otherwise completely smooth soup.
Ingredients: 40 g pumpkin seeds · ½ bunch fresh coriander
A coconut spiral, seeds, coriander
Before you start
With squash
Half sweet potato and half butternut squash gives a less sweet, more savoury soup. Roast the squash alongside — it needs roughly the same time; check with a knife.
More filling
Add a tin of drained chickpeas to the blended soup and blend again. It gains protein and becomes a full meal, while the flavour barely changes.
How long it keeps
Four days in the fridge, and it freezes beautifully — without the coconut milk. Coconut can split after thawing, so add it when reheating instead.
Sweet potatoes are not potatoes
They are a different plant entirely and behave differently: more sugar, less starch, faster cooking. In this recipe they cannot be swapped for potatoes without changing the whole character of the soup.
