Cook mushrooms and onion in vegan butter in skillet over medium heat, stirring occasionally, until onions are tender.
In a bowl mix coconut milk, vegetable broth and dried thyme. Pour the mixture over the mushrooms. Cook over medium heat, stirring occasionally for 5 minutes.
In a separate bowl mix cornstarch and 2 tbsp of coconut milk. Pour the mixture into a skillet.Boil and stir for 3 minutes.