Oven & Pan Pre-Heating : Position an oven rack in the lower third of your oven and preheat to 400°F (205°C). Place the empty heavy-duty roasting pan in the oven to get hot.
Prepare the Vegetables : Thoroughly wash and peel the root vegetables. Trim the ends and chop them into uniform 1-inch (2.5 cm) cubes. Cut the yellow onion into similar-sized wedges.
Create the Seasoning Slurry : In the large mixing bowl, whisk together the olive oil, fresh thyme leaves, smoked paprika, sea salt, and black pepper until well combined.
Coat the Vegetables : Add all the chopped vegetables and onion wedges to the bowl with the seasoning slurry. Toss thoroughly with your hands or a large spatula to ensure every piece is evenly coated in oil and herbs.
Initial Searing Roast : Carefully remove the hot roasting pan from the oven. Immediately tip the coated vegetables onto the pan, spreading them into a single, uncrowded layer. The hot surface will create an initial sizzle. Roast for 20 minutes.
Final Roasting & Caramelization : Remove the pan from the oven. Use a spatula to flip and toss the vegetables. Return the pan to the oven and roast for an additional 15 to 20 minutes. The vegetables are done when they are fork-tender with deeply browned, caramelized edges. Serve immediately.
