Ingredients:

• 4 tablespoons unsalted butter
• 1/2 medium onion, finely diced
• 1 stalk celery, finely diced
• 1 carrot, finely diced
• 1/4 cup all-purpose flour
• 4 cups unsalted or low-salt brown beef stock, preferably homemade
• 1/4 cup canned tomato puree
• Pinch salt
• 8 whole peppercorns
• 1 bay leaf
• 4 parsley stems, optional