Preheat your oven to 450°F (230°C).
Remove the marinated roast from the tray or container, pat it dry with a paper towel.
Keep the marinade, transfer it to a small pot and let it simmer over medium-low heat until it reduces by half. This process should take approximately 30 minutes. Set it aside to use for gravy later.
Season the beef with salt and freshly ground black pepper.
In a roasting pan, place the roughly chopped carrots, onions, garlic cloves, and celery along with fresh rosemary and thyme sprigs.
Place the seasoned roast on top of the vegetable and herb bed in the roasting pan.
Roast in the preheated oven for 15 minutes, then reduce the heat to 300°F (150°C).
Continue roasting for an additional 1 hour and 15 minutes for medium doneness.
Turn off the oven, and leave the meat inside for 45 minutes or until the core temperature of the beef reaches 130°F (55°C) when a meat thermometer is inserted.
When the sirloin tip roast is cooked, remove it from the baking dish, place it in a separate dish, cover it with tin foil, and let it rest for 20-25 minutes while preparing the gravy.