Preheat your oven to 425°F (220°C) to ensure the dish cooks evenly and achieves a slightly crispy texture.

Slice the smoked sausage into bite-sized pieces. Trim the green beans to remove stems or rough edges. Cube the red potatoes into 1-inch pieces for even cooking. Wedge the onion into medium-sized chunks.

In a large bowl, combine the smoked sausage, trimmed green beans, cubed red potatoes, wedged onion, olive oil, salt, pepper, and garlic powder. Toss thoroughly to coat all pieces evenly with oil and seasoning.

Transfer the prepared mixture evenly into a 9×13-inch baking dish. Cover the dish tightly with aluminum foil to lock in moisture during the initial bake.

Place the dish in the preheated oven and bake covered for 30 minutes. After 30 minutes, remove the foil and stir the mixture to redistribute the flavors.

Return the dish to the oven uncovered and bake for an additional 10–15 minutes, or until the vegetables are slightly caramelized and the sausage develops a crispy, flavorful exterior.

Remove the dish from the oven and allow it to sit for a few minutes. Serve as-is or garnish with crispy fried onions or fresh herbs. Store leftovers in the refrigerator for up to 3 days.