Celery-Root Bisque with Shiitakes

Ingredients

• 0.3 teaspoon pepper black to taste
• 3 rib celery stalks chopped
• 2 lb celery root with a knife and cut into 1/2-inch cubes peeled (sometimes called celeriac)
• 0.3 cup cup heavy whipping cream 
• 1 tablespoon juice of lemon fresh to taste
• 2 teaspoons salt to taste
• 0.5 lb shallots chopped
• 6 oz mushroom caps fresh sliced
• 0.5 cup butter unsalted
• 8 cups water 

Equipment

• bowl
• frying pan
• pot
• blender
• slotted spoon

Directions

1. Cook celery root, chopped celery, and shallots in 1/2 stick butter in a 5-quart heavy pot over moderate heat, covered, stirring occasionally, until softened but not browned, about 15 minutes.
2. Add water, salt, and pepper and simmer, uncovered, until vegetables are very tender, about 30 minutes.
3. Purée soup in batches in a blender until smooth (use caution when blending hot liquids), then return to pot.
4. Stir in cream and reheat bisque over low heat, stirring occasionally, about 5 minutes. Stir in lemon juice.
5. While bisque is reheating, melt 2 tablespoons butter in a 12-inch heavy skillet over moderately high heat until foam subsides, then sauté mushrooms with salt and pepper to taste, stirring, until golden brown, about 3 minutes.
6. Transfer mushrooms with a slotted spoon to a plate and add remaining 2 tablespoons butter to skillet. Cook butter over moderate heat, swirling skillet, until browned, about 2 minutes, then transfer to a small bowl.
7. Serve bisque topped with mushrooms and drizzled with brown butter.