This is one of my favorite soup recipes, and has been for about 15 years. It's adapted from The New Basics Cookbook--a book with several great soup recipes in my opinion. I've added the lemon juice, which seems a nice way to accentuate the flavor of almost any savory recipe, and also the grated Parmesan.
4 tablespoons unsalted butter
1 large onion, diced2+1/2 pounds carrots, peeled & sliced
2 ribs celery, with leaves, diced
8 cups chicken stock
1/2 cup chopped dill
salt, freshly ground pepper
generous pinch of cayenne
fresh lemon juice
Melt the butter in a large pot. Add the onions and cook over medium heat until soft, about 10 minutes. Add the carrots, celery, stock, 1/4 cup dill and cayenne. Bring to a boil, reduce heat and simmer for 40 minutes, or until carrots are tender. Let cool slightly. Puree the soup, in batches, in a blender. Return to the pot, stir in remaining dill and season with salt, pepper and a couple squeezes of lemon. Heat through and serve. Sprinkle with grated Parmesan, if desired.