Combine sauce ingredients in a small bowl and stir until smooth. Set aside.
Heat a large cast iron pan over high heat. While the pan heats, season the steak with salt and pepper, to taste and then rub with the oil. When the pan is hot, add the seasoned steak and sear well on both sides, about 5 minutes per side, or until the internal temperature measures 125ºF.
Remove steak to a cutting board to rest for 5 minutes.
Add the bowl of sauce to the now empty pan and turn off the heat. The residual heat will boil the sauce. Stir and then let sit for 2 minutes, or until bubbling and thickened. Season to taste with more salt, sweetener, or vinegar, as desired.
Slice the beef against the grain for the most tender bite. Then place atop a bed of coleslaw mix. Finally, drizzle with the sauce and garnish with cilantro.