Heat a cast iron skillet over medium-high heat until hot, about 2 minutes.
Blot any excess moisture from sliced steak with a paper towel. Add the steak to the skillet. Cook until cooked through, 4 to 5 minutes, stirring once.
While the steak cooks, make the sauce: Whisk together the aminos, vinegar, 2 tablespoons ghee, coconut sugar, garlic, salt and pepper.
Reduce the heat to medium. Move the steak to one side of the skillet and add the remaining 1 tablespoon ghee and the zucchini noodles. Sauté for 1 minute, then pour in the reserved sauce. Toss with tongs to coat the meat and noodles with the sauce.
Continue to cook until the sauce reduces, about 5 minutes longer. Divide the steak and noodle mixture between 2 bowls, top with the scallions and sesame seeds, and serve.