Combine the Zucchini, Onion, Italian Seasoning, and Olive Oil in a bowl. Toss to mix and set it aside.
Heat a large pot of water to boiling and season generously with salt. Add the pasta and cook to your favorite level of "al dente"
Reserve about 1 cup of the pasta water and drain the pasta.
While the pasta cooks, heat your grill to medium high. Place the sausage on the top rack. Heat a grill basket and add the zucchini onion mixture.
Grill until the sausage is browned and the zucchini is lightly charred.
Slice the sausage into 1/2 inch thick coins.
Combine the drained pasta, sausage, zucchini and the reserved pasta water in a large skillet over medium heat. Toss to mix everything together. Add the mozzarella and basil and toss once more to combine.