Cube the steak into bite size pieces. Trim any extra sinew off.

Cube the potatoes into bite size pieces and par cook the potatoes by boiling them for 5 minutes. This can be done on the stove top or simply in the microwave in a microwave safe dish with added water. You want them to still be a bit hard, but turning tender.

Lay out 4 pieces of aluminum foil, approximately 14×18 inches each. Lay 1/2 pound of beef onto each piece of foil and onto of that, 1/2 pound of potatoes. and top that with chopped jalapenos.

In a small mixing bowl, whisk together butter, parsley, salt, pepper, garlic, and Worcestershire sauce. Divide evenly and spoon onto the potatoes and beef. Lay a sprig of rosemary across the top.

Wrap up foil packets to close.