Cut the Zucchini - Trim the stem and end off the zucchini. Slice lengthwise into ½-inch thick pieces. Alternatively, cut into diagonal pieces. Place on a sheet tray.
Combine the Seasonings - In a small bowl, combine salt, Italian seasoning, black pepper, garlic powder, and onion powder.
Season the Zucchini - Brush both sides of the sliced zucchini with olive oil. Evenly season both sides with the salt mixture.
Grill the Zucchini - Preheat the grill or grill pan over medium heat between 350 and 375°F (160 to 177°C). Clean the grates and grease with olive oil. Place the zucchini slices at a 45-degree angle to the grates. This will give a nice char mark pattern and prevent the pieces from falling through the grates.Lightly press down to make contact with the grates. Cover and cook until golden brown lines form, about 4 to 5 minutes. Flip, cover, and cook until tender but not mushy, about 3 to 5 minutes.
To Serve - Transfer the pieces to a serving dish and garnish with chopped parsley and parmesan cheese (if using).
Notes
Storing: Cover and store grilled zucchini in the refrigerator for up to 5 days.
Reheating: Cover and microwave on high heat in 15 to 30-second increments until warm.