Combine prepared green pepper, cucumber and onion in a large, non-reactive pot. Stir in two cups of apple cider vinegar and bring to a simmer. Cook over medium heat for approximately 30 minutes, until the vegetables have cooked down a bit.
Drain the vegetables and return to the pot. Add remaining vinegar, sugar and the spices. Bring to a simmer and cook for five minutes. Remove pot from heat.
Fill jars, wipe rims, apply lids and tighten bands. Process in a boiling water canner for 10 minutes (starting time when pot returns to a boil).
When time is up, remove jars from pot and let cool on a towel-lined countertop. When jars are completely cool, remove the bands and test the seals. The relish is good to eat immediately. Store sealed jars in a cool dark place for up to a year.