To prepare cabbage, cut cabbage into quarters or eighths (depending of size of your cabbage head). Trim away any pithy or brown ends of the core, but leave the core intact. The core will hold the wedges together while roasting.
Arrange cabbage wedges on a baking sheet. Drizzle with olive oil and sprinkle with kosher salt. Bake 30 minutes, flipping wedges after 15 minutes so they brown evenly.
While cabbage is roasting, prepare vinaigrette. Whisk together olive oil, sherry vinegar, mustard, salt and pepper.
Serve cabbage wedges with vinaigrette and cheese, if using. Serves 4.