Our refined mushroom soup, toppedwith a poached egg, is beauty in abowl. It's delicious, too, thanks to simple but satisfying ingredients: driedand fresh mushrooms, tarragon, whitewine, Parmesan cheese.
Soak dried mushrooms in boiling water, covered, until soft, about 20 minutes. Lift out mushrooms; squeeze over liquid. Finely chop; set aside. Pour liquid through a fine sieve into a bowl; reserve.
Heat oil in a medium saucepan over medium heat until hot but not smoking. Add onion, garlic, and celery; cook, stirring occasionally, until soft, about 8 minutes. Add fresh mushrooms and salt; cook, stirring occasionally, until most of liquid has evaporated and mushrooms are soft, about 12 minutes. Raise heat to high. Add wine, reserved mushrooms and liquid, stock, and 1 1/2 cups water; bring to a simmer. Reduce heat to medium-low; cook 30 minutes. Add chopped tarragon.
Fill another medium saucepan 3/4 full with water; bring to a bare simmer over medium heat. Crack eggs into pan; cook until whites are set but yolks are slightly runny, 3 to 4 minutes.
Divide soup among 4 bowls. Transfer an egg to each bowl; divide cheese among eggs. Season each serving with pepper, and garnish with a tarragon sprig.