Roast peppers on barbecue or under broiler until skins are charred and peppers are soft. Scrape skin off when cool and remove seeds and pith. Chop.
Plunge tomatoes into large pot of boiling water for 1 minute, then remove to ice water bath. Peel, remove seeds and chop into desired size of pieces.
Dice onions. Finely dice hot peppers (if using). 1 hot pepper is ok for mild salsa.
Add all chopped vegetables to large pot. Add salt, sugar, cumin, garlic, tomato paste and lime juice. Bring to a boil over medium heat, then simmer for about 15 minutes. Salsa will reduce and thicken as it simmers.
Chop large handful of cilantro and stir into to salsa right before adding to jars.
Add hot salsa to jars, leaving at least ¼ inch space at the top. Wipe tops of jars.
Dip seals for a few seconds in hot water to soften. Place on jars, screw on rings without over tightening.
Prepare large canner pot for boiling jars. Bring water to a boil, then add jars until fully submerged and boil for 10 minutes for smaller jars or up to 15 for larger jars. Continue in batches until all jars are canned.
Cool on counter, undisturbed until lids pop. Lids should be inverted when properly sealed.