Preheat oven to 425 degrees. In a small bowl, whisk together olive oil, Worcestershire sauce, minced garlic, paprika, thyme, rosemary, oregano, basil, and salt. Set aside.
Bring a large pot of water to a boil with some salt. Add the potatoes and cook for about 10-12 minutes. Add the carrots for the last 5 minutes (add them after the potatoes have already cooked for 5-7 minutes). Drain the water.
Put the potatoes, carrots, chopped onions, and steak chunks in a large bowl. Mix evenly together. Pour the oil and spice mix over the top. Mix together, making sure everything is well covered with spices.
Evenly divide the meat and veggies onto 6 square pieces of tin foil. Heavy duty tin foil holds up the best, but regular tin foil should be fine. Put a half tablespoon of butter on the top of each portion. Seal up the tin foil well, rolling the tin foil around the top--this is important in making sure it won't leak in the oven.
Place packets directly on the middle rack. Cook for about 15-20 minutes, checking the meat temperature around 15 minutes and cooking to your preferred tenderness*. Once done to your liking, open them up and enjoy!