Prepare fresh garlic cloves by peeling and cutting the large pieces lengthwise into smaller pieces.
Create holes all over your beef tenderloin with a knife and push each garlic piece into a hole. Do that all over the meat so that the garlic is spread out.
Slice onion.
Combine black pepper, salt, thyme, and rosemary in a small mixing bowl.
Spread sliced onion in the Dutch oven and place meat over that.
Pour olive oil over the beef and sprinkle with the seasoning. Rub in all around the meat.
Add butter to the meat.
Preheat oven to 400° Fahrenheit/ 200° Celsius.
Take the beef tenderloin Dutch oven to the stove and sear the meat over a medium to high heat setting for about 5–10 minutes on all sides, or until the beef changes into a gray color all over.
Pour and stir broth in.
Cover the Dutch oven and place it into the oven.
Roast beef tenderloin at °. Decide how you want your beef, rare, medium, or well done. I cooked mine medium-rare to medium for a total time of 25 mins. *see Notes
Prepare slurry by combining all-purpose flour and water.
5 mins before you are done roasting, pour and stir slurry in. If you have a meat thermometer you can check the inner temperature too (*see Notes).
Uncover the Dutch oven and finish roasting meat for the remaining 5 minutes.
When done roasting, pour the sauce over the roast. That way it stays juicy.
Cut meat into slices and serve up hot with other sides f your choice. See post for serving ideas.
Video
Notes
Cook your meat either rare, medium rare, medium or well done at 400° Fahrenheit/ 200° Celsius:
rare for 14-18 mins and inner temp. 85-120 Fahrenheit or 30-50 Celsius
medium rare for 19-23 mins and inner temp. 130-145 Fahrenheit or 55-63 Celsius
medium for 24-26 mins and inner temp. 145-155 Fahrenheit or 63-68 Celsius
well done for 30 mins and inner temp. 160-170 Fahrenheit or 72-77 Celsius