Whisk together molasses, vinegar, oil, pepper, garlic, ginger, thyme, and red pepper flakes, and pour into plastic zip-top bag containing steaks. Seal tightly and flip a few times to evenly distribute marinade.
Set in refrigerator to marinate for 30 minutes to 2 hours, flipping bag occasionally.
Preheat gas or charcoal grill to 400 F degrees.
Remove meat and discard marinade. Season with salt and more pepper to taste.
Place steaks on oiled grates and grill for approximately 7 to 9 minutes on one side, or until moisture starts to pool on the top and beef releases easily from grates with tongs. Flip once, grilling on the other side for 6 to 8 minutes or until internal temperature reaches 135 F degrees with instant-read meat thermometer inserted into the thickest part of steak
Transfer plates to platter and let rest for 5 to 10 minutes before slicing against the grain.
*Double recipe if you’d like to have leftovers to make steak salad and beef breakfast bowl.