DO-AHEAD TIP: Marinate flank steak overnight or for at least 4 hours (see recipe).
In a large bowl, toss together steak strips and coconut flour until each strip is lightly covered (add more flour if necessary).
In a small bowl, place remaining ingredients, except coconut oil; whisk together into a nice, thick marinade.
Place steak strips in a large zipper-topped plastic bag and pour marinade on top; seal bag and turn to coat; refrigerate overnight or for at least 4 hours.
At time of cooking, melt the coconut oil in a large skillet or wok over medium-high heat. Add steak strips; cook and stir for 4 to 7 minutes.
Add remaining marinade and heat through; serve.