mary berry special: easy tomato soup with pesto
- 1 vegetable stock cube.
- 25g (scant 1oz) butter.
- 1 onion, peeled and finely chopped.
- 25g (scant 1oz) plain flour.
- 2 x 400g cans chopped tomatoes.
- 2 tbsp tomato puree.
- salt and freshly ground.
- black pepper.