Preheat a grill to medium-high heat (375 to 450 degrees Fahrenheit).
Slice the zucchini and squash on the bias, about 1/2” thick. Place it in a bowl and mix it with the olive oil, oregano, garlic powder, onion powder, and kosher salt.
Place the squash directly on the grill grates and grill for about 2 to 3 minutes per side (4 to 6 minutes total), until charred and tender. Taste and add a few more pinches kosher salt.