In a bowl, whisk together the marinade ingredients. Reserve 1/2 cup of the marinade for drizzling on the steak and a 1/2 cup of the marinade for the coleslaw. Place the remaining marinade into a gallon ziploc bag or bowl. Add the boneless beef to the remaining marinade and let sit in the fridge until ready to grill. You can marinade the steak an hour or several, however long you have is great.
When you are ready to begin grilling, turn an outdoor grill to medium-high heat. Remove the steaks from the marinade and place on the hot grill. Discard the rest of that marinade. Cook the steaks on both sides until some char marks appear and the edges of the steak are cooked. Cook steak as long as you would like for your desired doneness. Medium wellness seems great for this recipe.
While the steaks are cooking, prepare the coleslaw by placing the coleslaw cabbage into a bowl. Add the chopped cilantro and then drizzle with the extra reserved marinade, sour cream and mayonnaise. Toss until it's as coated as you desire. Set aside until steak is done.
Once the steak is cooked to your likeness, remove from the grill and let rest for 5 minutes. When ready to assemble tacos, cut the steak into thin strips or dices. Drizzle the cut steak with the reserved 1/2 cup of marinade.
Heat a flat griddle to medium heat and place several corn tortillas on the griddle. Fill each taco with some sliced or chopped steak. Let warm until tortilla is golden brown and a little crispy. Top the taco with coleslaw. Serve tacos warm and enjoy!
The picture is shown with red bell peppers and mangos in the coleslaw. You can add these or any other vegetables you'd like to that part of the recipe. Pineapple, green onions, avocados, etc. would all be great additions.