Heat the olive oil in a large pan, add the celery and zucchini/courgettes, and cook for 5 mins on a medium heat, stirring occasionally.
Add the tomatoes and gluten free flour. Cook for a couple of mins, stirring around to stop the flour from becoming lumpy. Add the turmeric and stock, cover and simmer for 30 mins.
Purée with a stick blender, then sieve if you want a really smooth texture. Serve hot with gluten free bread, if you like, or chill, then freeze for up to 2 months.
Recipe from Good Food magazine
1 tbsp olive oil
2 sticks celery, chopped
1kg zucchini/courgettes, sliced
1kg tomatoes, chopped
2 tbsp gluten free plain flour
½ tsp turmeric
2l chicken or vegetable stock from cubes
Gluten free bread, to serve (optional)