Trim any excess fat from the beef. Freeze the beef for about 1-2 hours to firm it up; this will make it easier to slice.
Using a sharp knife, slice the beef against the grain into thin strips, about 1/4 inch thick. For chewier jerky, slice with the grain.
In a bowl, combine soy sauce, Worcestershire sauce, brown sugar, black pepper, garlic powder, onion powder, smoked paprika, and red pepper flakes. Mix well.
Place the sliced beef in the marinade, ensuring each piece is coated. Cover and refrigerate for at least 4 hours, or overnight for more flavor.
If using a dehydrator, preheat it to 160°F (70°C). If using an oven, preheat it to the lowest setting, usually around 170°F (77°C).
Remove the beef from the marinade and pat it dry with paper towels. Arrange the strips on the dehydrator trays or a lined baking sheet in a single layer with space between them.
Dehydrate in the dehydrator for 4-6 hours or bake in the oven for 4-6 hours, flipping every hour until the jerky is dry and firm but still slightly pliable.
Once done, let the jerky cool completely. Store in zip-top bags or an airtight container in a cool, dry place.