Chorbet Basal (onion soup)

Instructions

1. Thinly slice the onions along the grain.
2. Heat the olive oil in a large saucepan over medium heat and cook the onions for 15 minutes, stirring, until golden.
3. Sprinkle over the flour and stir for 2 minutes to cook it lightly.
4. Gradually pour in the hot stock, whisking to avoid lumps.
5. Add the diced potatoes if using, and season with cumin, salt and pepper.
6. Simmer gently for 20 minutes until the vegetables are tender.
7. Blend lightly to thicken the soup if you like, then stir in the lemon juice and parsley just before serving.