Whisk together all of the marinade ingredients. Place the marinade in a zipper-top bag with the steaks and massage to coat. Place the steaks in the refrigerator for at least 2 hours or overnight (Michaela also suggests freezing the steaks for future use; the steaks will marinate as they thaw).
About 30 minutes before cooking, remove the steaks from the refrigerator to bring them closer to room temperature.
Preheat the grill to medium heat and cook to desired temperature.
Notes
For those who prefer a little less sweetness, I was thinking that eliminating or reducing the brown sugar and relying on the sweetness of the soda would be worth trying.