Creamy mushroom soup with fresh herbs

Name: Creamy mushroom soup with fresh herbs
Prep time: 15 min
Cook time: 15 min
Total time: 30 min
Cuisine: European, British
Ingredients: 1 tablespoon olive oil; 1 carrot (peeled and diced); 1 onion (diced); 1 stalk celery (diced); 1 tablespoon unsalted butter; 3 cloves garlic (minced); 1 lbs champignons mushrooms (thinly sliced); salt to taste; freshly ground black pepper; 1/2 teaspoon dried thyme; 2 tablespoon all-purpose flour; 4 cups chicken broth; 1/2 cup sour cream; 1 tbs chopped fresh parsley leaves; 1 tablespoon chopped fresh dill leaves