60 g butter
1 onion, sliced
1.5 kg very ripe tomatoes, seeded and roughly chopped
1 litre Vegetable Stock
2 tbps potato flour
salt
freshly ground black pepper
Melt butter and gently sauté onion in a large saucepan until softened.
Add tomato to pan, then cover and cook gently until tomato is very soft, about 20 minutes.
Pass through the medium disc of a food mill and return to pan.
Add stock and heat to simmering point.
Mix potato flour to a smooth cream with a little cold water. Stir a good ladleful of soup into potato flour mixture, then return it to pan. Stir until soup returns to a simmer.
Cook for a further 15 minutes and add salt and pepper to taste.
Pass through the finest disc of a food mill if there are too many fragments for your liking. For the smoothest texture of all, whizz the soup in a blender.