Preheat oven to 425 degrees and line a large sheet pan with parchment paper.
In a medium bowl, combine all of the marinade ingredients and whisk together. Set aside.
Add the red potatoes to a large bowl and pour 1/3 of the marinade over the potatoes. Toss the potatoes until they are well coated. Dump the potatoes out onto the prepared sheet pan. Roast the potatoes for 15 minutes.
While the potatoes are roasting, add the chicken sausage, sliced onion, and green beans to the large bowl. Pour the rest of the marinade over the sausage slices, onion slices, and green beans. Toss to coat.
When the potatoes have roasted for 15 minutes, remove sheet pan from the oven. Stir up the potatoes to turn them and then add the sausage mix to the sheet pan. Cook the potatoes, sausages, and veggies for another 15-20 minutes. Everything should be fork-tender and have a slight char.
Remove from oven and serve hot. Top with a little extra grated Parmesan if desired. Enjoy!