Remove the gills of the portobello mushrooms caps by scraping them with a spoon. A grapefruit spoon is helpful if you have one. Chop the mushroom caps, potatoes and carrots into bite size pieces and dice the onion and garlic.
Add the oil to a large pot and bring the heat to medium high. Once hot add the onion and garlic and cook for 3 minutes. Now add the mushrooms, red wine, tomato paste, Worcestershire, soy sauce, salt, thyme, and pepper. Saute on medium for 5 minutes.
Now add the potatoes, carrots, and broth and stir well. Bring to a boil, then lower to a simmer for 30 minutes. Remove ½ cup of the broth from the pot and combine it with the corn starch to make a slurry. Return this to the pot and simmer for 15 more minutes or until the potatoes and carrots are tender. Top with chopped parsley and serve.