Roasted Sausages with Cabbage and Squash

Name: Roasted Sausages with Cabbage and Squash
Ingredients: ½ kabocha squash (1 pound), seeds removed, cut into ¾-inch wedges; 7 tablespoons extra-virgin olive oil, plus more for drizzling; Kosher salt and freshly ground pepper; ½ head green cabbage (1 pound), cut lengthwise through core into 4 wedges; 4 sweet Italian sausages (1 pound total), each pierced with a fork in a few places; 1 medium red onion (8 ounces), thinly sliced into rings; Leaves from 2 sage sprigs; 1 tablespoon apple-cider vinegar; 1 teaspoon Dijon mustard