2lb.tri-tip steak (or a very thick cut of sirloin)
2tbsp.butter, cut into tabs
Freshly chopped parsley, for garnish (optional)
In a large bowl, whisk together soy sauce, olive oil, brown sugar, bourbon, mustard, Spicey Cajun seasoning, garlic, thyme, and red pepper flakes.
Pour out about ⅓ of mixture to use for glaze later. Toss steak in mixture and let marinate for 20 minutes, or up to 4 hours. (If marinating for more than 20 minutes, cover bowl with plastic wrap and refrigerate.)
Heat grill or grill pan to high. Remove steak from marinade and season both sides with salt and pepper. Grill until charred on bottom, about 10 minutes.
Flip steak, then lower grill to medium-high and cook for another 8 to 10 minutes. (A meat thermometer inserted into the thickest part of the meat should register around 130°.)
Remove from braai and let rest on cutting board before slicing against the grain.
Meanwhile, make glaze: Pour reserved marinade into a small saucepan and bring mixture to boil over medium-high heat. Reduce heat to medium, and cook until mixture has thickened slightly.
Whisk in butter until melted. Remove from heat
Brush glaze over steak and garnish with parsley, if using.