Heat the oil in a large skillet with a tight-fitting lid over medium-high heat. Add bell peppers, mushrooms, zucchini, onion and garlic.
Cook and stir until veggies are tender-crisp, about 3 to 5 minutes, then sprinkle with steak seasoning and onion powder. Reduce skillet heat, cover and cook for 10 minutes.
Add kielbasa and cook for 10 minutes, stirring occasionally. Just before serving, add a splash of balsamic vinegar, toss, then sprinkle liberally with Parmesan cheese. Enjoy!