Trim silver skin or connective tissue off the tenderloin with a very sharp thin knife.
Place the tenderloin in a Ziploc bag. Add in 4 tbsp of the olive oil, balsamic vinegar and brown sugar. Securely close the Ziploc bag. Massage the oil and vinegar into the tenderloin.
Marinate for 2 hours or overnight.
Preheat oven to 450 degrees F. Line a cookie sheet with aluminum foil and spray with oil.
Heat 2 tbsp of olive oil in a skillet over high heat. Sear the tenderloin on all sides. It can burn quickly, so watch it carefully.
Place the seared tenderloin on a nonstick cookie sheet with a rim.
Cut small slits into the meat and place a slice of garlic into each slit. Combine coarse salt and pepper with the thyme and rub meat with blend.
Roast in hot oven for 20-30 minutes or until a meat thermometer inserted into the center reads 145 degrees F.
Remove from the oven. Let meat rest for 10 minutes, transfer to a carving board, slice and serve.