1. Fill a large pot with water and bring to a boil. Meanwhile prepare an ice bath. Core out the stems from the tomatoes and slice a shallow "X" in the bottom of each tomato.
2. Blanch the tomatoes in boiling water for 30-60 seconds, then transfer to ice bath. Remove the skin from the tomatoes.
3. Chop the tomatoes into small chunks and set aside.
4. In a large pot heat olive oil. Add chopped onion and sauté over low heat until golden, about 7-8 minutes. Add crushed garlic and sauté for 2 minutes more.
5. Add chopped tomatoes to the pot, season with salt, oregano and basil. Bring the mixture to a boil, reduce the heat and simmer for 60-90 minutes, until reaches desired consistency (until almost all the liquid has evaporated and the tomatoes are reduced to a thick, jam-like consistency). Stir frequently. At the end add the vinegar, stir and turn the heat off.
6. If you prefer smooth tomato sauce, puree the sauce using a hand blender. Transfer to a jar.
Recipes you can make with homemade tomato sauce: