Hi Lisa, yes, all the sources I’ve read say that bottled lime juice can be substituted for vinegar. Bottled is the key, not freshly squeezed. And adding some roasted green pepper should be perfectly fine as well. But if you have any doubt you can always buy some pH test strips (you can find them online, like on Amazon) to make sure the acidity level is correct.
If you live in a town with a noticeable Mexican or Latin American community, chances are you’ll be able to find a specialty store carrying these goods, if not there’s always the good, old, world wide web. Many websites carry and even specialize in Mexican and Latin American ingredients. If you live in Denmark like me, try out chilihouse.dk for example, they’re a great one stop resource and they’re not even paying me to say that!

Some of the online recipes and comments totally scare me to think what some people are doing, either by direct choice or lack of canning knowledge, that endangers their families’ lives! There was a lot of unexplained illness and death in the old days that I think could be partly due to food storage issues. It’s the opposite of the Lottery–you want to be the 1 in a million to win the lottery, but you DON’T want to be the 1 in a million to win the botulism contaminated canning jar! Canning is one process that you MUST follow the safety rules whether you’re a natural rule follower or a rebel!

Delicious!!!  As far a second knowing how many tomatoes to use, you mentioned somewhere that it was three sheet pans of halved tomatoes.  Using this information, I collected my garden tomatoes on my counter by placing them on my baking sheet.  When I had my baking sheet full plus another half, I knew I had enough tomatoes (or at least that I would be close once I drained them).  Turned out great!!  Even my daughter who can tell handle spicy foods LOVES this salsa!
This year I wanted to can salsa again, and I’d just had a little bit of that Mexican salsa (served with a quesadilla at a local organic restaurant, if you’re curious) and it reminded me that that was what I wanted to go for.  So, I set into my kitchen with 54 lbs. of tomatoes and decided to use some of them to make a small batch of salsa.  If it was just “okay” I’d have a few pints to eat up through the year and that would be it.  If it was great, I’d make more batches.  It’s pretty safe to say I’ll be making more. 🙂

OMG this is so good!! I made a batch at 7am for a bbq this afternoon and ate half of it for my breakfast, so had to replenish it with another can of tomatoes (only had a can of chopped tomatoes left, which worked fine, plus another pinch of all the other ingredients… Amazing! Only thing I had to change was using garlic powder as I had no fresh, still fine. Used 1 green chili and half a red, no seeds, perfect! And 1/4 tsp sugar, as I’m not a huge fan of sweetness. Thank you so much, this is my go to Salsa now :)) Going to make your hummus now too!
This is a great salsa for beginners in Mexican cuisine. There are other salsas that are a little bit more complicated, and which require that you char the tomatoes and other veggies first. This salsa roja recipe, however, just requires that you blend the raw vegetables together, and then cook them with a bit of olive oil before adding onions and cilantro. 
UPDATE: Since many of you have asked about a weight measure for the 10 cups of tomatoes, as I've been canning the salsa the last few days, I've done a little experimenting/research. Basically, I've found it varies GREATLY depending on variety. When I used SIX pounds of garden tomatoes + Roma (the paste tomatoes probably only made up about 1/3 of the total), after taking the skins off, lightly crushing, and draining, the yield of tomatoes to use in this recipe was about 2 1/2 cups. When I used TWO pounds of only Roma/paste tomatoes, after taking the skins off, lightly crushing, and draining, the yield of tomatoes to use was a little over one cup. I tend to err on the side of over draining the tomatoes, if anything, so that makes a difference as well. For me, because I usually use paste tomatoes in this recipe, I would plan on around 18-20 pounds (give or take) of Roma/paste tomatoes to get the 10 cups for this recipe...and even more if using tomatoes with a higher water/lower flesh content.
Hey Beth – sorry about that. The notes somehow went missing. I’ll add them again, but here’s a great article about canning salt. Basically, you can sub in kosher salt or even table salt (although use a bit less since the granules of table salt are finer)…it’s best to try to use a kosher salt without any additives (canning or pickling salt is pure salt without any anti-caking agents) if possible.
Douglas, I was just wondering about using the iron skillet or comal and the tomatoes. I tried a different recipe the other day and used my iron skillet to toast the ancho chilies, tomatoes and serrano peppers it called for. After blending all the ingredients, I used the same skillet to heat and cook the finished sauce. I only thought about it after the fact and wondered if the acidic sauce changed in flavor by using the iron skillet. I am sure our grandmothers used their iron for everything and never worried about the acid in them, so I am sure this question is moot, but I still want to know. I am not a very good cook, even though I try, and last weeks sauce did not turn out very tasty. I am going to give this one a try and hope it comes out better. Thank you for posting this.
As you will notice when we dive a little further into these recipes, Mexican food has a stunning range of somewhat special ingredients. From Masa Harina, the essential ingredient of corn over a wide array of chilies either fresh, dried or ground to Mexican oregano and tomatillos. Some of these may at first glance seem foreign and difficult to come by, but fear not we’ll discuss the individual ingredients as we go and they’ll be easier to come by than you think.