+ Original recipe has roasting the tomatoes at 500˚. This is great and definitely gets a wonderful flavor, but cleaning up the sheet pan is a pain (since you can't use parchment!) If you're up for the challenge, roast at 500˚ for about 30 minutes, checking occasionally, until tomatoes have a nice char on them.
+ For a little extra smokiness, add a bit of diced chile pepper (either in adobo sauce or a dried one that has been soaked in water). Start with just a bit and add more as desired for heat.
+Use other tomatoes as desired but try and stick with low water, paste tomatoes. These make for a thicker salsa.