Partially freeze the beef. Place the trimmed beef in the freezer for 45–60 minutes. Slightly firm meat is easier to slice thin and even.
Slice the meat. Cut against the grain into 1/8–1/4-inch slices for chewier jerky, or with the grain for a more tender bite.
Keep thickness consistent.
Mix the marinade. In a large bowl, combine Dr Pepper, soy sauce, Worcestershire, brown sugar, jalapeños, red pepper flakes, garlic powder, onion powder, black pepper, smoked paprika, and vinegar. If using curing salt, whisk it in thoroughly.
Marinate. Add the beef to the marinade, making sure every piece is coated. Cover and refrigerate 8–24 hours.
For best flavor, aim for 12–18 hours. Stir once midway if you can.
Drain and pat dry. Remove the beef from the marinade and lay the strips on paper towels. Pat dry to remove surface moisture; this speeds up drying and improves texture.
Preheat and prep. Oven: Preheat to 170–180°F (or the lowest setting).
Line baking sheets with foil for drips. Place wire racks over sheets and lightly grease the racks.
Dehydrator: Preheat to 160°F (if adjustable). Lightly oil trays to prevent sticking.
Arrange the strips. Lay beef in a single layer without overlap.
Press jalapeño slices onto some strips if you want visible bits of heat on the finished jerky.
Dry the jerky. Oven: Prop the oven door open slightly with a wooden spoon to allow moisture to escape. Dry for 3.5–5.5 hours, flipping once halfway. Time depends on thickness and your oven.
Dehydrator: Dry 3–6 hours, rotating trays as needed.
Check for doneness. Jerky should be firm and dry but still pliable.
Bend a piece: it should crack slightly along the surface but not snap in half. If it’s soft or damp in the center, keep drying.
Cool completely. Let jerky cool on the racks. Cooling helps set the texture and prevents steam from adding moisture to storage containers.
Condition the jerky. For best shelf stability, place cooled jerky loosely in a clean jar or bag for 24 hours at room temp, shaking once or twice.
If condensation appears, it needs more drying.