In a cast iron pot on medium-high heat seal the beef on both sides using a small amount of oil (avoid making it black). Transfer the beef to a medium bowl. Preheat oven to 325 degrees F / 160 degrees C.
Add to the cast iron pot the carrots, garlic, and onion, and cook 10 minutes or until vegetables are browned and tender, stirring occasionally. Wisk flour in 1/2 cup warm water and stir into pot along with tomato paste, 3/4 teaspoon salt, and 1/2 teaspoon coarsely ground black pepper; cook 1 minute, stirring. Add wine and heat to boiling, stirring.
Return meat and any meat juices to the cast iron pot. Add thyme and mushrooms; heat to boiling then cover and bake for 1.5 hours or until meat is fork-tender, stirring occasionally. Just before stew is done, cook peas as label directs. Stir in peas and keep cooking for another 10min.