Step 1: Prepare the Steak and Potatoes
Cube the Steak: Start by cutting the steak into bite-size pieces. Make sure to trim off any extra sinew to ensure tender and enjoyable bites.

Cube and Par Cook the Potatoes: Cut the red potatoes into bite-size pieces. Par cook the potatoes by boiling them for about 5 minutes. This can be done on the stove top or in a microwave-safe dish with added water. The goal is to have the potatoes still a bit firm but starting to turn tender.

Step 2: Assemble the Foil Packs
Prepare the Foil Sheets: Lay out four pieces of aluminum foil, each approximately 14×18 inches. This size is perfect for creating individual servings and ensures there’s enough room to fold and seal the edges.

Add Steak and Potatoes: Divide the cubed steak and potatoes evenly among the four pieces of foil. Each piece should get about 1/2 pound of steak and 1/2 pound of potatoes.

Add Jalapenos: Sprinkle the finely chopped jalapenos over the steak and potatoes. Adjust the amount of jalapenos according to your preferred level of heat. Removing the seeds will reduce the spiciness.

Step 3: Make the Garlic Butter Sauce
Prepare the Sauce: In a small mixing bowl, whisk together the softened butter, chopped parsley, salt, pepper, granulated garlic, and Worcestershire sauce. This mixture will provide the rich, buttery garlic flavor that makes this dish so delicious.

Top the Steak and Potatoes: Divide the butter mixture evenly among the four foil packs. Spoon the mixture directly over the steak and potatoes, ensuring even coverage.

Add Rosemary: Lay a sprig of rosemary on top of each pack. The rosemary will infuse the dish with its fragrant, earthy aroma.

Step 4: Cook the Foil Packs
Wrap the Foil Packs: Carefully fold up the edges of the foil to create sealed packets. Make sure the packets are well-sealed to keep the steam and juices inside during cooking.

Cook the Foil Packs: You have two options for cooking:

Oven: Preheat your oven to 375°F (190°C). Place the foil packs on a baking sheet and cook for 25-30 minutes.

Grill: Preheat your grill to 400°F (200°C). Place the foil packs directly on the grill and cook for 15-20 minutes.

Step 5: Serve and Enjoy
Check for Doneness: Carefully open one of the packets to check if the steak is cooked to your desired level of doneness. If you prefer well-done beef, you may need to cook the packets for an additional 5-7 minutes.

Serve: Once the steak and potatoes are cooked to perfection, carefully remove the foil packs from the oven or grill. Be cautious when opening the packets, as the steam and juices will be very hot.

Garnish and Enjoy: Transfer the contents of each foil pack to a plate, or serve directly from the foil for a rustic presentation. Garnish with additional chopped parsley if desired.