olive oil • ground cumin • sweet paprika • kosher salt • ground coriander • turmeric • ground black pepper • Cayenne pepper • large head cauliflower (about 2½ pounds), trimmed and cut into bite-size florets • large red onion, cut into ¼-inch wedges • Pita, naan or flatbread, for serving • coarsely chopped parsley, plus more for serving •