Step 3) Reduce heat in skillet to medium heat. Add onion and cook 2 to 3 minutes until onion is just getting soft. Add garlic and cook 1 minute. Add mushrooms and thyme, stirring often. Cook for 3 to 4 minutes or until mushrooms are tender. Add red wine and stir well to deglaze any browned bits in skillet. Add half of the beef broth, bring to a boil and continue to cook for 2 to 3 minutes. Whisk corn starch into remaining beef broth and add to skillet. Bring to a boil and reduce heat to very low.