Combine soy sauce, Worcestershire sauce, apple cider vinegar, brown sugar, smoked paprika, garlic powder, onion powder, black pepper, and red pepper flakes in a bowl. Whisk until the sugar is dissolved.
Place the elk meat in a large resealable bag. Pour the marinade over the meat, ensuring all pieces are coated. Marinate in the refrigerator for 8-12 hours, turning the bag occasionally.
Remove the meat from the marinade and pat dry. Arrange on dehydrator trays or a baking sheet lined with parchment paper if using an oven.
Dehydrate at 160°F for 4-6 hours, or until the jerky is dry but still pliable. If using an oven, keep the door slightly open to allow moisture to escape.
Let the jerky cool completely before storing in an airtight container.