Preheat a grill to medium-high heat (375 to 450 degrees Fahrenheit).
Slice the zucchini into into 4 thin slabs, about 3/4-inch or so. Place it in a bowl and mix it with the olive oil, oregano, garlic powder, onion powder, and kosher salt.
Place the zucchini directly on the grill grates and grill for about 3 to 4 minutes per side (6 to 8 minutes total), until charred and tender. Remove from the grill, taste and add more salt if necessary.