From Jerry Traunfeld's The Herb Farm Cookbook:
2 medium leeks
1 1/2 T dried whole coriander seeds
3 T unsalted butter
1 lb large sweet carrots (about 4), peeled and cut into 1/4 slices
1/2 C dry white wine
2 t finely chopped fresh ginger
3 C fresh carrot juice
1 t salt
2 C water
1 large bunch fresh spearmint (about two ounces)
2 t freshly squeezed lemon juice
For the garnish: tiny mint leaves or thinly sliced mint leaves
1. Cut off and discard the tops of the leeks at the point where they turn from light to dark green. split them lengthwise in half, keeping the roots attached so that the layers will not fall apart, and wash thoroughly. Thinly slice the leeks, then discard the root ends.
2. Put the coriander seeds in a small dry skillet and place in over medium heat. shake the pan contstantly until the seeds begin to darken in color and smell fragrant. Do not overcook. Pour them onto a paper towel to stop the cooking, then using the towel as a funnel transfer them to a spice mill and grind very fine. if you don’t have a spice mill, use a mini processor or blender.
3. Prepare the vegetables. Melt the butter in a medium heavy-bottomed saucepan over medium heat. Add the leeks and cook for 5 minutes, stirring occasionally. Add the carrots, wine, and ginger, and cook uncovered until all the liquid has boiled away, about 15 minutes, then continue to cook until the vegetables are slightly browned, about 10 minutes. Don’t rush the step for it allows the natural sugars to slowly caramelize. As the vegetables cook, keep scraping the bottom of the pan with the spoon to gather up andy brown bits. Deglaze with the white wine.
4. Add the carrot juice, coriander, and salt. bring to a boil, cover and gently simmer over heat until the carrots are very tender, 20-30 minutes.
5. While the soup is simmering, make a mint tea. Off the heat, submerge mint in boiled water, cover and let steep for about 20 minues, then strain and squeeze all the liquid out of the leaves.
6. Finish the soup: put half of the soup in the container of an electric blender (you can use a food processor instead, but the soup might not be as smooth). Hold the lid down with a dry towel and turn the blender on at a low speed so that the soup doesn’t splash up, then gradually increase the speed to high. Add half of the mint tea. Blend the soup until is is creamy and very smooth. Return the pureed soup to a new clean saucepan and repeat with the remaining soup and tea. When all of the soup is pureed, add the lemon juice and gently reheat. Taste and add the additional salt or lemon juice if needed. Serve garnished with mint leaves.