Heat a large skillet over medium heat.
Add the ground turkey sausage and cook, stirring and breaking it up with a spatula, until fully cooked and no longer pink, about 6–8 minutes; drain excess fat if needed.
Stir in the sesame oil, then add shredded green cabbage, shredded carrot, shredded red cabbage, sliced yellow onion, minced garlic, and minced ginger.
Pour in the soy sauce and sprinkle with kosher salt and black pepper; toss to combine.
Cook, stirring occasionally, until the vegetables have softened but still retain a bit of crunch, about 3–4 minutes.
Remove from heat and garnish with chopped green onions and chopped cilantro, if using, then serve.