1. Peel the potato and cut it into cubes. Put them in a saucepan or soup pot with the broth. (NOTE: You may substitute vegetable broth or even plain water if you prefer a vegetarian dish.)

2. Trim the leeks and wash them well, using only the white and pale green portion, and slice thin (or peel the onion and chop it coarsely). Trim the fennel bulb and chop it coarsely. Put all the vegetables and the bay leaf in the soup pot with the potatoes, adding a little water if there's not enough liquid to cover the veggies. Season to taste with salt and white pepper, but taste-test before salting if the broth is already salty. Bring to a boil, reduce heat, cover, and simmer over low heat for 20 to 30 minutes or until the vegetables are soft.

3. Remove the bay leaf and blend the soup into a thick puree. Put the saffron threads in a little warm water and add to the soup. Stir in the creme fraiche (or optional butter) and serve, garnished if you like with a sprig or two of the lacy fennel leaves.

WINE MATCH: This will work with just about any dry white wine. I like it with a rich, slightly oxidative white from the Rhone or Provence or Southern Italy, although on occasion when we're serving this as a light, simple dinner, we may skip wine entirely, saving the calories for a taste of dessert wine afterward.