This is my mom's "secret" recipe. I'm not doing anyone any favors though - I feel for my own sake I have to document this. You wouldn't believe how many times I can only recall six ingredients and then forget the seventh - and the one I forget seems to be different every time.
You have to be a tinkerer to enjoy this recipe - note I have not put any amounts in. I will say that if you're going canned for the tomatoes (and that's what I usually do, unless tomatoes are at peak), you will want to have a 28 ounce can of peeled plum without italian spices. When you chop those up in the blender, the rest is all taste and feel.
Peeled plum tomatoes
Salt to taste
Put ingredients one at a time in a blender. You will want to use the setting for the style of "chunkiness" you want in your salsa - I usually do "chop" for a salsa that still has texture but is more like a taco sauce. You will want to taste after each addition to your liking - the ingredients should be added in the order above. Be careful with the oregano - if you add too much, you'll have marinara and won't be able to recover from it w/o adding an entire new tomato can.
I have a dear chef friend Adam who once for a party added white rum to the above recipe. It's also great to leave this completely chunky and not use a blender but rather old-fashioned fine hand-chopping. The rum version had a great kick (sort of like the effect tequila has on fajitas), but when I told my Mother of our great addition I was met with dead silence on the other end of the phone, so use your judgement.
This will keep jarred in the fridge for up to two weeks and makes a great low-calorie topping to chicken, burritos, chips, fingers, etc...