Step 1

In a Dutch oven, melt 2 tablespoons of butter over medium heat. Add the mushrooms and cook until they're tender and the edges brown, three to four minutes. Transfer them to a plate and set aside.

Step 2

Add the remaining 2 tablespoons of butter to the Dutch oven and reduce the heat to medium. Add the onion and carrot and cook until tender, four to five minutes. Add the garlic and tomato paste and cook one minute longer.

Step 3

Stir in the flour and cook until brown, two to three minutes. Slowly whisk in the wine. Cook until the sauce thickens, one to two minutes. Stir in the vegetable broth and bring it to a simmer. Editor's Tip: Given the color of the tomato paste and browned vegetables, it might be difficult to judge when the flour darkens. Stir the flour while it cooks so that it blends thoroughly into the butter-coated vegetables, and then keep going a minute longer to ensure it loses its raw, powdery mouthfeel and taste.

Step 4

Add the mushrooms back to the pot. Stir in the Worcestershire sauce, bay leaf, thyme and rosemary. Simmer for 8 to 10 minutes or until the sauce slightly reduces.

Step 5

Discard the bay leaf. If desired, stir in sour cream. Serve the mushroom bourguignon over hot polenta or mashed potatoes, garnished with parsley.