Sweet potato soup with harissa & tahini
It’s that time of year again: soup season. This is in fact the second reason to be happy about autumn, the first I posted about yesterday: pies!
Harissa is one of my favourite spice blends, originating from the North African region of Maghreb, it is full of flavour and works so well with a wide variety of vegetables. Here I have used harissa to balance the sweetness of the vegetables and the lemon tahini adds a little zing and nuttiness. I particularly like the Spice & Green harissa blend made by my friend Melanie Hadida, but you could use a good quality supermarket version or even make your own. Here’s a recipe by Mr Ottolenghi if you want to to give it a try.
Ingredients
Serves 6-8
1.3kg sweet potato (unpeeled)
4 red onions, chopped roughly
3 large garlic cloves, grated
2 tsp harissa spice blend
1 vegetable stock cube (low salt Kallo)
1.6L water
1.5 tsp sea salt
Toasted sesame seeds - optional to serve
Lemon tahini
4 tbsp tahini
Juice of half a lemon
75ml water
1/4 tsp sea salt
Method
Preheat the oven to 180ºc.
Put the sweet potatoes on a baking tray and roast in their skins for about 45mins-1 hour or until they’re soft right through. This will vary depending on size.
Heat 1 tbsp rapeseed or olive oil in a large deep pan and add the onions, cook for 20 minutes on low. Peel the sweet potatoes while the onions are cooking.
Once the onions are softened add the harissa and warm through for a few minutes to release the flavours. Then add the crumbled stock cube, water, salt and sweet potato (break up with a spoon). Bring to the boil and simmer for 10 minutes.
Make the lemon tahini while the soup is cooking. Put the tahini and salt in a jug or jar, squeeze in the lemon, whisk with a fork before adding the water whisking again.
Turn off the heat and use a hand blender to thoroughly blitz the soup to a smooth consistency.
Serve with a drizzle of tahini (about 1/2 tbsp) and a good pinch of sesame seeds.
Tip
Tahini goes very thick when you first add water, keep going it’ll loosen up. Or use a small blender to avoid this problem.
You might need to add a little water to the tahini each time you use it as it tends to thicken up after being stored for a day in the fridge.
Sesame seeds toast quickly and easily in a dry frying pan. Just sprinkle evenly and place on a medium heat, watching careful as they will suddenly colour. You want a pale gold brown.