Start by prepping everything before you begin to cook. Stir fries come together quickly, so it's best to be ready to go.
Dice up the red onion and set it aside.
Stir together the coconut aminos (soy sauce/tamari) with sesame oil and red pepper flakes in a small bowl. Set the sauce aside while you begin to cook.
Increase the heat to high and add the zucchini. Stir fry stirring only as the zucchini browns. High heat helps you achieve nice seared edges without the zucchini turning into mush while it cooks.