Begin by gathering your ingredients. You will need 6-7 pounds of beef, diet Dr Pepper, lemon juice, brown sugar Swerve, coarse black pepper, coarse salt, rosemary, garlic cloves, and steak spice.
Add the marinade ingredients to a 9x13" aluminum pan or large baking dish.
Cut the beef to 1/4" thickness, being sure to trim off excess fat and tendons. Layer this in the marinade and allow to rest for 12-24 hours in the refrigerator. We purchased a whole sirloin from Costco when it was on sale and made two batches of beef jerky with it.
Remove the beef from the marinade, pat it dry with paper towel, sprinkle with salt and pepper (if desired), and place in a single layer on the smoker.
Cook at 160°F for 4-6 hours, flipping the beef once halfway through. Keep an eye on any hot spots (our Traeger is hotter at the front) and thinner slices of beef that may smoke faster.
Remove from the smoker and enjoy. We store this for up to a month in the fridge or longer in the freezer.