I always start by preheating my oven to 400°F so it's fully heated by the time the turkey goes in. While that's happening, I coat the bottom of a large baking dish with olive oil. This little step keeps the vegetables from sticking and helps them caramelize slightly as they roast.
Next, I scatter the carrots, onion, and red pepper across the bottom of the dish. I drizzle a bit more olive oil over them and toss everything so each piece gets lightly coated. This bed does double duty, flavoring the broth and turning into an easy side dish.
I pat the turkey tenderloin dry, then sprinkle it generously with salt and pepper on all sides. Patting it dry first actually helps the seasoning stick better and encourages browning later. I place the seasoned turkey right on top of the vegetables.
In a separate bowl, I stir together the white wine, chicken broth, garlic powder, and crushed rosemary. I pour this mixture evenly over the turkey and vegetables, making sure some liquid pools at the bottom. This keeps everything moist while it roasts.
I cover the baking dish tightly with foil and slide it into the oven. It roasts for about 30-40 minutes, and I always check the internal temperature with a meat thermometer at the thickest part. I'm looking for 165°F before moving to the next step.
Once the turkey hits temperature, I remove the foil and switch my oven to high broil for 4-5 minutes. I keep a close eye on it here because broilers work fast, and I want a golden, slightly crisp top without drying it out.
I let the turkey rest for about 5-10 minutes before slicing, which keeps all the juices inside instead of spilling onto the cutting board. I slice it against the grain into medallions and serve it right over the roasted vegetables.