Combine all seasoning ingredients. Set steaks out to reach room temperature. Brush oil on both sides of the steaks and press seasoning mixture into all areas of steaks. Set aside and prepare the grill.
Heat grill to 450 - 475 degrees F. When the grill reaches temperature and steaks are room temp, sear steaks on the hottest part of a grill and grill 2 to 4 minutes. Rotate steaks a quarter-turn and grill another 2 to 4 minutes. Flip steaks to the other side and grill for 2 to 3 minutes rotate 1/4 turn and grill another 2 to 3 minutes. (The second side takes less time.) At this point, move steaks to a cooler area of the grill and continue cooking until your preferred doneness. Test the internal temperature for doneness with an instant-read thermometer.
Allow steaks to rest 5 minutes before cutting.
Start Sauce while steaks are grilling and resting.
Red Wine Sauce
Cook onion in one tablespoon of butter over medium heat for 1 to 2 minutes or until tender. Add wine and broth to onions and bring to a boil over medium-high heat. Cook for 10 to 12 minutes or until reduced by about 1/3. Next, reduce the heat to low. Combine room temperature butter and flour in a small bowl and mix until smooth. Whisk into the wine sauce. Cook and stir for one minute or until sauce is thickened. Serve warm over steaks.
Cornstarch or flour can be used, but is not a necessity, to thicken the sauce. It's good without.