Instructions:

1. Sear the beef:

Heat the olive oil in a large skillet over medium heat.
Add the tenderloin pieces to the skillet in batches, making sure they are in a single layer.
Sear the beef for 2-3 minutes on each side, until browned. Remove the seared beef from the skillet and set aside.
2. Sauté the aromatics:

Add the chopped onion and minced garlic to the same skillet.
Cook the aromatics until soft and fragrant, about 3-4 minutes.
3. Deglaze the pan:

Pour the red wine into the pan and scrape up any bits from the bottom with a wooden spoon.
Simmer the wine for 2-3 minutes, reducing slightly.
4. Make the sauce:

Stir in the beef stock, soy sauce, Worcestershire sauce, tomato puree, dried thyme, and dried rosemary.
Season the sauce with salt and black pepper.
5. Simmer the beef tips:

Return the browned beef to the pan, making sure it is covered in the sauce.
Cover the pan and reduce the heat to low.
Simmer the beef tips gently for 1-2 hours, or until the meat is tender and the flavors have melded well.
6. Thickening the sauce:

In a small bowl, mix the cornstarch and water until it forms a paste.
Gradually stir the mixture into the pan, thickening the sauce.