Preheat a grill to medium-high heat (375 to 450 degrees Fahrenheit).
Slice the 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, kosher salt, and red pepper flakes (if using).
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 pinches of additional salt if necessary.