To make the tomatoes easier to peel, first cut a small "X" just through the skin at the bottom of each tomato. Then blanch them for just 60-90 seconds in boiling water, then rinse with cold water. Peel the tomatoes (starting at the "X" where you scored them), then continue to core and chop the peeled tomatoes. Remove seeds if desired. Set tomatoes aside.
Choose a large saucepan or pot (a 2-quart size is ideal). Add the 1/3 cup of olive oil and heat over medium heat, then add in the diced onions. Cook onions until tender. Next add the garlic and cook for 1 minute longer.
Now add the chopped tomatoes to the pot along with the salt and bring mixture to a boil. Immediately reduce heat to low. Next add in all the fresh herbs, along with the red pepper flakes if desired.
Simmer until sauce thickens, around 40-50 minutes. NOTE: For an even thicker sauce, add 1 tablespoon of tomato paste while simmering.
Serve over zoodles, or whatever you like.