Pre-heat oven to 425ºF and adjust an oven rack to the lower and middle part of the oven.
On a sheet pan add onion, cauliflower, potatoes, oil, salt pepper, thyme and spices and mix together.
Bake on the lower rack for 20 minutes.
Remove from the oven, stir the veggies and potatoes to ensure even cooking. Place the apples and kielbasa on top and drizzle the sausage with a bit of oil and place back in the oven for 25 minutes, stirring halfway through, until the sausage is starting to brown and the veggies are cooked through.
Serve immediately with a touch of spicy or brown mustard.
