Heat the oil in a large saucepan.
Tip in the onions, carrot and peppers.
Cook gently for 15 mins, to soften.
Add the garlic and chilli, and cook for
a few mins more. Pour over the chopped
tomatoes and 800ml of the stock. Bring
to the boil and simmer for 10-15 mins
until the veg is completely tender.
Meanwhile, mix the yogurt, cucumber
and mint in a bowl, and season.
Blitz the soup with a hand blender until
smooth, using the extra stock to thin if it
has become too thick. Heat through,
season and spoon into bowls. Serve
with a dollop of the yogurt mixture
on top and a drizzle of olive oil.