Enjoy the classic flavors of a steakhouse dinner at home with this clever all-in-one recipe. We've upgraded grill-friendly London broil steak with a garlicky marinade enriched with Worcestershire sauce. The sides--red creamer potatoes and sauteed spinach--are also done on the grill and served with an herb butter that will please the entire family.
Chop 2 cloves of the garlic and add to a large resealable bag. Add the steak, oil, vinegar, basil, red pepper flakes, 1/4 cup of the Worcestershire sauce and 1/2 teaspoon each salt and pepper. Seal the bag and turn several times to coat the meat. Refrigerate, turning the bag occasionally, at least 4 hours and up to overnight.
When ready to cook, prepare a grill for high heat.
Chop 1 clove garlic and add to a medium bowl. Add 6 tablespoons of the butter, the remaining 1 teaspoon Worcestershire sauce, half of the shallots and 3/4 teaspoon salt and stir together until well combined. Fold in the parsley and chives; set aside.
Stack two 18-inch pieces of foil on a work surface. Pile the potatoes in the middle, dot with 1 tablespoon butter and sprinkle with 1 teaspoon salt. Bring the foil up and over the potatoes and seal tightly. Put the potatoes on the grill, cover the grill and cook for 10 minutes.
After the potatoes have cooked for 10 minutes, remove the steak from the marinade, letting the excess drip off, and put it on the grill next to the potatoes; leave the other half of the grill empty for the spinach. Grill the steak, flipping every 4 to 5 minutes, until a thermometer inserted into the thickest part registers 130 degrees F, 16 to 20 minutes for medium rare. Transfer the steak to a cutting board and let rest 10 minutes before thinly slicing. Let the potatoes continue to cook until tender throughout, about 25 minutes total. (They should be ready about when the steak is.)
Meanwhile, put a large cast-iron skillet on the empty side of the grill. Chop the remaining 3 cloves garlic and add to the skillet with the remaining shallots and 1 tablespoon butter. Heat until the butter is melted and the shallots and garlic are softened, about 3 minutes. Add the spinach and cook, tossing with tongs, until wilted and most of the moisture has evaporated, about 8 minutes.
Push the spinach to one side of the skillet. Being careful of the steam, open the packet of potatoes and dump them into the other side of the skillet. Remove the skillet from the grill. Spread the herb butter over the steak and potatoes before serving.