Place beef in a resealable bag or container.
In a small bowl whisk together the seasoning, red pepper flake if using, curing salt and water. Pour over the meat and seal. Shake to coat.
Refrigerate the meat for up to 8 hours, shaking or massaging every hour or so to get the marinade distributed and absorbed evenly.
Remove meat from the marinade and add to a jerky gun. Squeeze out onto Nesco trays. Do not overlap meat.
Add the dehydrator top, set to maximum temperature setting and dehydrate for 5 hours, rotating the trays (bottom to top) every 2 hours or so.
To test for doneness remove a piece and let cool slightly. Try to bend the meat. If it gives and starts to tear at the bend it is done. If it bends without tearing return to the dehydrator and let it run another 15 minutes and test again. If the meat is crunchy it is overdone but still good. It's really personal preference as to how you like your jerky. Soft, chewy, crunchy. There's no wrong here.
Let cool before storing in an airtight container.