Slice bell peppers into long strips and cut onions into half rings.
Combine ingredients together into a large pot. The peppers will not be covered by liquid at first, but they will eventually shrink and cause a perfect amount of marinade.
Bring it to boil and cook for about 10 minutes, until the peppers turn soft. Store in a refrigerator or can it, by follow the instructions below.
Sterilize the jars and preheat the oven to 215 °F. Wash the jars and lids and place them in the oven for about 15 minutes or until completely dry. With the help of a canning funnel, place peppers into jars, while they are still hot.
Close all lids very tightly. Flip them upside down and keep it for several hours; this process helps seal the lid. Store in a cool place. They can be stored up to a year.