Deb Perelman's Mushroom Bourguignon

INGREDIENTS

• 2 tablespoons butter, softened
• Egg noodles, for serving (buttered potatoes or farro work well too)
• 1 small yellow onion, finely diced
• 1 cup pearl onions (thawed if frozen)
• 2 cups beef or vegetable broth (beef broth is traditional, but use vegetable to make it vegetarian; the dish works with either)
• 1 teaspoon fresh thyme leaves
• 1 cup full-bodied red wine
• 1 1/2 tablespoon all-purpose flour
• 2 tablespoons olive oil
• 2 cloves garlic, minced
• Salt and freshly ground pepper, to taste
• 2 pounds 1/4-inch sliced portobello or cremini mushrooms
• 1/2 carrot, finely diced
• Sour cream and chopped chives or parsley, for garnish (optional)
• 2 tablespoons tomato paste