Mix steak, potatoes, olive oils, salt & pepper and garlic in a large bowl. Toss with seasonings.
Split the potatoes and steak between four foil sheets measuring 12x12 inches. The foil should be tightly wrapped around the contents to create foil packs. Grill steaks and potatoes on high heat for approximately 10 minutes each side, or until they are cooked through. Or bake the foil tightly around the contents for between 20-25 minutes.
Garnish the dish with fresh thyme and parsley, and serve immediately