Clean, rinse and pat dry the beef (eye round roast or London broil).
Slice against the grain and about ⅛" to ¼" thick. Place the sliced meat in a ziplock bag or airtight container. Tip: place meat in the freezer for 30 -45 minutes before slicing. It will be easier to slice.
In a small bowl: combine brown sugar, soy sauce, Worcestershire sauce, pepper, onion, garlic and mix.
Pour the sauce over the meat. Make sure to coat the meat well. Refrigerate for 24 - 36 hours. Toss and flip the meat at least twice.
Preheat the oven to 175°F.
Line 2 baking sheets with aluminum foil for easy cleaning later. Set baking racks over the lined baking sheets. Place sliced meat on the rack in a single layer (do not over crowd the meat).
Place both baking sheets in the oven. Cook for 3- 4 hours or until the meat has dried out to your liking. Rotate both baking sheets from top to bottom and vice versa after 2 hours of cooking. Flip the the meat if needed.
Store beef jerky in an air tight container or ziplock bag for up to 2 weeks.