Marinate beef strips overnight or for at least 4 hours (see recipe).
Prepare marinade: In a large bowl, whisk together first 7 ingredients (gingerroot through crushed red pepper flakes).
Place beef strips in a large zipper-topped plastic bag; pour marinade over the top, seal the bag and turn to coat; refrigerate overnight or for at least 4 hours, turning occasionally if possible.
At time of cooking, melt the coconut oil in a large wok or skillet over medium-high heat; add onion and bell pepper; stir-fry for 1 minute.
Add contents of bag to the skillet; cook and stir for 10 to 15 minutes or until beef strips are cooked to desired level of doneness.