Prep. Soak the wooden skewers in water for 20 minutes. Then, preheat the grill to medium-high.
Prepare the steak. Slice the flank steak against the grain into 16 to 20 strips; they should be between ⅛-inch to ¼-inch thick. Season the steak slices with cumin, salt, and pepper.
Skewer it. Thread the steak onto the skewers, accordion style. Set aside.
Make the chimichurri sauce. In a blender, combine the olive oil, chopped cilantro, garlic, red wine vinegar, lemon juice, pepper flakes, salt, and pepper. Pulse until thoroughly combined, then set aside.
Grill. Brush the grill grates with olive oil. Place the steak skewers on the grill and cook for about 1 minute per side, or until browned and grill marks appear.
Finish and serve. Remove the steak skewers from the grill and let them rest for a couple of minutes. Bruth the steaks with the chimichurri sauce, garnish with red pepper flakes, if you like, and serve.