Heat vegetable oil in a large pot or Dutch oven over medium-high heat.
Add beef cubes in batches, searing them until browned on all sides. Remove beef and set aside.
In the same pot, add diced onion and cook for 4-5 minutes until softened.
Add minced garlic and cook for 1 minute until fragrant.
Stir in tomato paste and cook for 2 minutes.
Return the browned beef to the pot.
Pour in beef broth and water, stirring to combine.
Add carrots, celery, potatoes, Worcestershire sauce, dried thyme, dried rosemary, and bay leaves.
Season with salt and black pepper to taste.
Bring the stew to a boil, then reduce heat to low and cover.
Simmer for 2 hours, stirring occasionally, until beef is tender and vegetables are cooked through.
Remove bay leaves from the stew.
In a small bowl, whisk together all-purpose flour and cold water until smooth to make a slurry.
Slowly stir the slurry into the stew and cook uncovered for 10 minutes to thicken.
Add frozen peas, corn, and green beans to the stew and cook for an additional 5 minutes.
Let the stew cool completely before portioning into freezer-safe containers.
Label and freeze for up to 3 months.
To reheat, thaw overnight in the refrigerator and warm on the stove over medium heat until heated through.
Garnish with chopped fresh parsley before serving.