Preheat your grill to medium-high heat or your oven to 400°F (200°C).
In a large bowl, combine the steak cubes, sliced potatoes, sliced onion, minced garlic, and olive oil. Season with salt, pepper, and any additional herbs or seasoning of your choice. Toss everything together until well coated.
Tear off four large pieces of aluminum foil, each large enough to wrap one foil packet.
Divide the steak and potato mixture evenly among the foil pieces, placing it in the center of each piece.
Fold the foil over the steak and potato mixture to form tightly sealed packets, making sure to crimp the edges to prevent any juices from leaking out.
Place the foil packets on the grill or in the oven and cook for about 20-25 minutes, or until the steak is cooked to your desired level of doneness and the potatoes are tender. You can carefully open one packet to check for doneness if needed.
