In a gallon size zip lock bag mix together all marinade ingredients. Add flank steak; refrigerate for at least 4 hours. One hour before grilling, remove steak from refrigerator and let set on counter. Meanwhile, heat grill to medium high heat. Remove steak from marinade and discard leftover marinade
Place steak on grill and cook for 5 minutes on first side, turn over and cook an additional 3 to 5 minutes or until thermometer reaches at least 145 F. Slice steak across grain into thin slices; set aside, keep warm.
In medium skillet over medium high heat add 2 tablespoons sesame oil, red pepper, carrot, and red onion. Cook, stirring occasionally, for 2 to 3 minutes or until vegetables are crisp tender. Add spinach and 1 teaspoon water; cover, cook for 1 more minute or until spinach is wilted.
To assemble tortilla: Place about 2 ½ ounces steak down center of one flour tortilla, top with 2 tablespoons vegetable mixture, sprinkle with ½ teaspoon sesame seeds. Roll up or fold in half to serve. Repeat with remaining tortillas and ingredients.