The steak and corn can be grilled up to a day ahead and stored in the refrigerator, in separate containers; serve them cold or at room temperature. The chimichurri can also be made up to a day ahead; store it in the refrigerator, in a jar with a thin layer of olive oil on top. Shake to combine before serving, at room temperature.
It's a good idea to place the plastic bag holding the steak and marinade on a rimmed baking sheet or in a baking dish, in case of any leaks.
This recipe is one of our Better Basics: 10 New Takes on Family Favorites, see the others.