One can indeed use a pressure canner for canning salsa . I always use Roma tomatoes and never use the tomatoe paste (optional) in the recipe . It never turns out to liquidity or mushy ,not ever . Very certain the reason for that is the Roma’s are a meaty tomato. I have tried the water bath method as well with this recipe , both have the same consistency. I pressure can at 10 lbs. of pressure for 15 min. Adjust lbs. of pressure for your elevation .
Do take a look at this post about how to choose hot peppers, when making your decision, but if you are just starting out, we would recommend starting with jalapenos. Jalapenos will give your salsa a flavor similar to a lot of store-bought brands, and they can be anywhere from mild to spicy, depending on how much veining appears on the individual pepper.
I think that garlic will work fine. You can use a water bath canner or a steam bath canner – but you need either one of those to properly seal the jars. Sorry for the incorrect link. I’ve fixed it:

I added a tea spoon of fine ground hot pepper. now thats the slight hot I like and no tomato paste. I like it wet …Great recipe. the first time I ever made salsa and I am glad I found the perfect recipe.. on top of it all. its just like a recipe of a so called semi friend. that had his own recipe I liked and he wouldnt give it up. well ..he can bite this. now!! I got it. if not better ..ha ha !! you and your grand mother knew your stuff… Thanks !!