Sauté onion, leek and fennel in olive oil then add the other ingredients and cook. Saffron is added before mixing, keeping a few potatoes for decoration. Serve according to your taste with crouton, rouille, grated cheese, possibly poached egg.
Start by peeling and chopping onion. Wash fennel bulbs and remove the stems. Chop them. Wash leek and chop it as well.
In a large saucepan or cast iron pan, heat 3 to 4 tablespoons of olive oil. Sauté onion, leek and fennel. Add salt and pepper, stir. Let it fry over medium heat for about ten minutes, until vegetables softens.
Meanwhile, zest an orange (as thin as possible, ideally with a grater more than a zester) and cut garlic into strips. Wash and peel potatoes (cut them in half or quarter if they are big).
Possibly deglaze the onion – leeks – fennel white wine and stir a few minutes until wine evaporates.
Add hot water, garlic, orange zests, bay leaf, tomato paste and potatoes (which should be covered with liquid). Cook for 20-25 minutes until all vegetables are soft.
When cooked, add saffron and stir. Remove the bay leaf and a few potatoes (kept aside decoration). Mix the soup. Adjust the amount of potato mixed or decorative depending on your taste.
Serve the soup into a soup tureen (is that the right word in English for soupière?) or indivifual bowls, non mixed potatoes cut into pieces in a dish as a side or dropped in the soup. With as said above croutons (possibly rubbed with garlic), rouille and grated cheese.