Preheat the oven to 400°F (200°C). Line a large baking sheet with aluminum foil and lightly coat it with non-stick cooking spray. Set aside.

Prepare the ingredients: Rinse the baby potatoes and pat them dry. Cut them in half. Slice the turkey sausage into thick rounds and chop the onion into large chunks.

Combine in a bowl: In a large mixing bowl, add the sausage, potatoes, and onions. Drizzle with olive oil and toss well to ensure even coating.

Season the mixture: In a separate small bowl, mix the sea salt, black pepper, smoked paprika, and Cajun seasoning. Sprinkle the spice blend evenly over the sausage and potato mixture. Toss again to distribute the spices thoroughly.

Transfer to the baking sheet: Spread the mixture out on the prepared sheet pan, ensuring the ingredients are in a single layer for even roasting.

Roast the dish: Place the baking sheet in the oven and bake for approximately 50 minutes. Halfway through cooking, stir the mixture to promote even browning.

Check for doneness: Insert a fork into the potatoes to test their tenderness. If needed, bake for an additional 5–10 minutes until the potatoes are fully cooked and lightly crisped.

Serve: Remove from the oven, let sit for 2 minutes, then serve warm. Optional: garnish with chopped fresh parsley or serve with a side of sour cream or aioli.