When making a fresh tomato based dish never use stainless steel, tin or aluminum bowls. The acidity of the tomatoes will react. Stick with glass, ceramic, pottery or corning ware bowls.

In a large bowl add sliced tomatoes and salt. Stir to sweat the tomatoes. This is the acid in the dish and is why you don't need vinegar. Taste the tomatoes as they sweat and add more salt to keep them sweating - but not too much so that salt overtakes the flavor of the tomatoes. You will notice the juices starting to build. Add pepper to your liking and stir.

Add olive oil, basil and stir. Cover with plastic wrap and let the ingredients marry. Stir every so often. As the flavors start to develop I normally add more basil for a deeper level and will sometimes add more olive oil.