At the end of each summer, I harvest the last peppers, chop them and combine them with chopped onions to freeze for year-long seasonging. I use onions that I have harvested from this spring's crop. (I plant onions and garlic in the fall so that I can harvest full crops by the end of May, clearing that garden space for my summer vegetables, like tomatoes and - yes - these peppers.)
I grow both white and yellow onions every winter. Each year I think I'll grow some red onions -- I then promptly forget to order sets or seeds! My favorite are the yellow onions but, I have to say, raised in our raised beds where there is little elemental sulfur, all of our onions are incredibly sweet.
So, anyway, I chop and chop until I have a large bowl of chopped onions. And then I chop and chop peppers. Then I mix the two bowls together.... and spoon one cup amounts into 'zip' snack bags. Believe it or not, I whip up about 100 of these little baggies. And I'm ready all winter with amazingly fresh tasting onion/pepper mix ready to saute for omelettes, quiches, soups, pasta sauce....