A light soup, healthy and easy to make. Milk and flour are used as the thickening agents, and this method of giving body to otherwise watery dishes is a very ancient one (see Introduction).
In a heavy medium pot, sauté onion in oil until transparent, about 5 minutes.
Add flour and stir for a few minutes until flour is fragrant. Slowly pour in milk, stirring all the time, preferably with a wire whisk to prevent lumps.
Stir in the chopped spinach, coriander, salt, and pepper. Bring to a quick boil, then let it simmer gently on low heat, cove