Rosemary & Red Wine Pan Sauce

Bahan-bahan (4 porsi)

• 1 teaspoon butter (more if desired)
• 1 sprig fresh rosemary (chopped, or ½ teaspoon dried)
• 2 cloves garlic (minced)
• 1 cup beef broth (low sodium)
• ½ cup red wine (or beef broth)
• ½ teaspoon balsamic vinegar
• salt and pepper to taste