01 - Preheat oven to 425°F (220°C). Line a large sheet pan with parchment paper or foil for simplified cleanup.
02 - Evenly distribute the sliced cabbage, apples, and red onion across the prepared sheet pan.
03 - Position the sausages on top of the arranged vegetables and fruit.
04 - In a small mixing bowl, vigorously whisk together the maple syrup, mustard, olive oil, apple cider vinegar, salt, and black pepper.
05 - Generously drizzle the prepared glaze over the sausages and vegetables. Gently toss all components to ensure even coating, then arrange them in a single layer for optimal roasting.
06 - If utilizing fresh thyme, sprinkle the leaves evenly over the sheet pan contents.
07 - Roast for 25 to 30 minutes. Midway through the cooking time, turn the sausages and stir the vegetables. Continue roasting until the sausages are browned and thoroughly cooked, and the cabbage is tender and caramelized.
08 - Serve hot, spooning any accumulated pan juices over the top for added flavor.