Don't know if this will work for your recipe, but I've made tomato sauce and added too much salt. This worked! I sliced one raw peeled potato into the sauce and continued cooking the sauce-worked like a charm. I removed the potato before I served the sauce. The potato was delicious too! It's an old trick.
You could try it in your salsa. Do you cook your salsa; maybe it would work. I'd love to have your recipe too! Good luck!