Partially freeze the eye of round roast for 1-2 hours; this makes it much easier to slice thinly.

Using a very sharp knife, slice the beef against the grain into uniform strips, about 1/8 to 1/4 inch thick. Trim off any visible fat, as fat can cause jerky to spoil faster.

In a large non-reactive bowl, whisk together the soy sauce, Worcestershire sauce, apple cider vinegar, liquid smoke, brown sugar, garlic powder, onion powder, black pepper, red pepper flakes (if using), smoked paprika, and pink curing salt (if using).

Add the sliced beef strips to the marinade, ensuring all pieces are fully submerged and coated. Use your hands to mix thoroughly.

Cover the bowl and refrigerate for at least 6-8 hours, or preferably overnight (up to 24 hours), to allow the flavors to penetrate the beef. Stir occasionally if possible.

Remove the beef from the marinade and pat each strip thoroughly dry with paper towels. This step is crucial for efficient dehydration and to prevent a leathery texture.

Arrange the beef strips in a single layer on your dehydrator trays, ensuring no pieces are overlapping.

Set your dehydrator to 160°F (71°C) if using pink curing salt, or 145°F (63°C) if not, to ensure food safety.

Dehydrate for 4-8 hours, or until the jerky is dry, firm, and pliable but not brittle. It should bend without breaking. The exact time will depend on your dehydrator, the thickness of the meat, and the humidity.

Check for doneness after about 4 hours, and then every hour or so. To check, cool a piece to room temperature and bend it. If it cracks but doesn't break, and you see fibrous white strands (not red or wet), it's done.

Once done, let the jerky cool completely on a wire rack at room temperature for several hours (or overnight) to prevent condensation and mold formation during storage.

Store the cooled beef jerky in airtight containers or resealable bags at room temperature for up to 1-2 weeks. For longer storage (up to 1-2 months), refrigerate it.