In a large stockpot on medium temperature, add oil and chopped onion; saute 5 minutes or until onions are translucent; then add garlic; combine and cook for 2 minutes
1 tablespoon olive oil, 1 cup onion, 1 tablespoon garlic
If using whole peeled San Marzano tomatoes, pulse them and their juice in food processor (1-2 minutes) and add to onion mixture; if using crushed tomatoes, just add them to the onion mixture
56 ounces San Marzano Italian Tomatoes
Add tomato paste, dried Italian seasonings and red pepper flakes; NOTE: if using fresh italian herbs, don't add them now; we'll add them at the end
6 ounces tomato paste, 2 tablespoons Italian herbs
Bring sauce to boil for 5 minutes and stir; reduce heat to low; cover; stir frequently
Allow sauce to simmer for at least 30 minutes; (for best results, allow to cook on low for 50 minutes); taste and season with salt and pepper;
Add red pepper flakes (optional); If using fresh herbs, add them now and allow to cook for 5 minutes
1 teaspoon crushed red pepper
Add salt and pepper to taste
½ teaspoon salt, ½ teaspoon pepper
Serve over warm pasta or refrigerate up to 5 days
Notes
If your store doesn't have crushed San Marzano tomatoes, buy whole or diced and pulse them and their juice in the food processor
Do not cook tomatoes in a cast iron skillet; the acidity interferes with the iron and gives off an unpleasant flavor.
If the tomato sauce starts to splatter and spew, turn the heat to simmer and add 3-4 tablespoons of butter and ½ cup water
Herbs:
The ratio of fresh to dried herbs is 3:1. If using fresh herbs, use 3 tablespoons and add them in the last 5 minutes of simmering (after you've tasted and adjusted for salt and pepper.)