It needs to be cooked ahead of time so that the flavors are blended and you can taste it and make sure it’s how you want before canning. With the big pot for canning, I have a quilted hot pad under them instead of a rack. I never bought a rack because the hot pads work just fine. You need something under the jars but it can be as simple as a kitchen towel (I have not broken a jar in 3 years! So it must be okay, lol). I have some posts on the water bath method that explain my equipment in more detail.
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 !!