Wash peppers, cut in half, stem, place cut side down on baking sheet. (You can also remove some or all of the seeds where a lot of the heat is if you wish.)
Peel garlic, put on baking sheet
Peel onion, cut into thick (2 cm / ½ inch) slices, add to baking sheet.
Put tray in oven, bake until garlic cloves are soft -- about 20 minutes.
Remove garlic cloves, chop, put in a large pot.
Put tray back in oven, and bake until onion is tender -- about another 15 minutes. Peppers should be starting to char a bit and the pepper skins should be getting wrinkled.
Remove tray from oven.
Let tray also stand 15 minutes to cool a bit.
Meanwhile, juice the limes. Set juice aside.
Wash and finely chop the fresh coriander; set aside.
Take skin off tomatoes, coarsely chop, add to pot where garlic is.
Coarsely chop onion, add to pot.
Chop garlic, add to pot.
Peel peppers. Discard skin.
Finely chop the peppers, add to pot.
Bring pot to a boil, stirring frequently.
Reduce heat, and let simmer uncovered 2 minutes.
Stir in the prepared lime juice, fresh coriander and salt.
Ladle hot sauce into heated jars, leaving 2 cm (½ inch) headspace.
Debubble, adjust headspace.
Wipe jar rims.
Put lids on.
Process in a water bath or steam canner.
Process jars for 20 minutes; increase time as needed for your altitude.