Slice your jalapeños and serranos into ¼” thick slices and set them to the side.
Add the apple cider vinegar, sugar, brown sugar, and spices to a pot. Bring to a rapid boil while stirring to dissolve the sugar.
Once the mixture is boiling, add your jalapeños and reduce the heat to a simmer. Let simmer for 10 minutes until the jalapeños have softened.
Remove the peppers from the liquid with a slotted spoon. Bring the mixture back up to a boil for 3 minutes, then reduce the heat to medium and let simmer for 10 more minutes to reduce by about half.
Transfer the boiled peppers into a large mason jar (or airtight container).
Once the liquid starts to thicken and get syrupy, you can pour it into the mason jar right on top of the peppers.
Let it cool fully before adding the lid, then store in the fridge for one week (up to three months).
Notes
Jalapeños —both red and green jalapeños will work. I like adding a bit of additional spice, so I add a few serrano peppers to the mix.