You're going to need a large bowl. And I mean large. Like 8-quart large. The pretzels and nuts need room to move around when you stir, so don't use anything too small. You'll also want a sturdy spoon or a large wooden spoon for stirring. Optional but helpful: have some ziplock bags on standby. Some people prefer to shake the mix in bags instead of stirring with a spoon.
In your large bowl, combine the pretzels and mixed nuts. Pour in the butter-flavored oil and stir really well to coat everything evenly. Make sure every pretzel and nut gets some of that oil coating. This takes a few minutes of stirring, but it's important because the oil carries the seasonings. The mixture should look wet at this point, like all the pretzels and nuts are glistening with the oil.
Sprinkle the ranch dressing mix evenly over the coated pretzels and nuts. Add the dried dill. Add the cayenne pepper. Stir everything together really thoroughly, making sure the seasonings are distributed evenly throughout the mixture. You don't want any pockets where the seasoning is concentrated. You want every pretzel and nut to have a little bit of flavor. This step takes a good 3-5 minutes of stirring to do properly, but it's worth it.
This is where patience becomes important. You need to let the mixture sit for at least 3-4 hours. During this time, the seasonings will absorb into the pretzels and nuts, and the oil will dry slightly, creating that crunchy, flavorful coating. But here's the key: you can't just leave it alone and walk away. Every hour or so (roughly every 60 minutes), give it a good stir. This stirring prevents the seasonings from settling to the bottom of the bowl. The heavier seasoning particles have a tendency to sink, so stirring redistributes them. You're essentially stirring from the bottom of the bowl to the top, making sure everything gets moved around.
After about 4 hours, start checking the texture. The mixture should be getting drier and crunchier. The oil should be drying rather than being wet. The seasonings should be adhered to the pretzels and nuts. Depending on the weather and humidity in your area, this could take 4 hours or it could take up to 24 hours. On a dry day, it might be done in 4 hours. On a humid day, it could take much longer. The hotter and drier your climate, the faster this process goes.
Keep stirring every couple of hours as long as the mixture seems wet or oily. There's no exact timeline because it really depends on your specific humidity and temperature situation. You're looking for the pretzels and nuts to feel relatively dry to the touch, not wet or overly oily. Once it reaches that texture, you're done waiting.
If you don't want to stand there stirring repeatedly, you can use the ziplock bag method instead. After combining everything in Step 3, distribute the mixture into large ziplock bags (gallon-sized bags work well). Instead of stirring in the bowl, shake the bags vigorously every hour or so. This achieves the same result as stirring but requires less effort and less space. Most people find this method easier, especially if you're making large batches.
Once your mixture is dry and fully seasoned, transfer it to airtight containers. Glass jars or plastic containers with tight-fitting lids both work great. Store in a cool, dry place. Properly stored in an airtight container, this snack mix will stay fresh and crunchy for 2-3 weeks. In hot or humid climates, it might get slightly stale sooner, but properly sealed, it should keep well.