Begin by peeling or scalding off the skins of the tomatoes if desired. Finely chop the 10 pounds of fresh tomatoes and place them in a large stockpot, initiating a simmer to reduce the tomatoes.
While the tomatoes simmer, finely chop the 2 pounds of onions and 4 pounds of peppers of your choice. For those with sensitive skin, use gloves and ensure thorough handwashing before any contact.
Add the chopped onions, peppers, and other ingredients (6 tsp salt, 1 tsp pepper, 2 cups vinegar) to the simmering tomatoes. Allow the mixture to simmer until your preferred thickness is achieved; this may take a few hours. If using cilantro, it's best added towards the end of the process. Once the desired thickness is attained, let the mixture undergo a low boil for 10 minutes.
Pack the salsa into clean, hot quart jars, or adjust the quantity by halving the recipe and using pints if preferred, leaving a 1/2-inch headroom. Seal the jars and process them for 15 minutes in a simmering hot-water bath. This process ensures a safe seal, and a flavorful and well-preserved homemade salsa.