Prepare cherry peppers by removing stems and seeds and rinsing clean. Reserve some of the seeds to add later.
Put cherry peppers, onion, garlic, and desired amount of seeds into a food processor. We used the seeds from 4 peppers. The more seeds you add, the hotter the relish will be. Add seeds to taste. Pulp mixture until finely chopped.
Transfer cherry pepper mixture to a large skillet with a tablespoon of olive oil. Set heat to medium. Stir in vinegar and sugar.
Cover and cook for 30 minutes. Check to make sure it isn't drying out. If so, add water. Cook uncovered for an additional 30 minutes. The liquid should be mostly cooked away by the end of the hour.
Remove from heat. Allow to cool. Store in a glass jar.