Place tomatoes, tomato paste, parsley (roughly chopped), garlic, oregano, garlic and pepper in a food processor. Blend until smooth. Can also use an immersion blender.
Place olive oil in a frying pan and heat over medium heat. Add onion and sauté until soft, about 2-3 minutes.
Pour in blended tomato mixture and chicken broth. Simmer for 30 minutes until thickened. Stir occassionally.
Notes
Use high-quality canned tomatoes for the best flavor. San Marzano tomatoes are a great option and give the sauce a rich, authentic taste.
Don’t skip sautéing the onions and garlic first. Cooking them in olive oil before adding the tomatoes creates a deeper, richer flavor base.
If you don't have a food processor, use an immersion blender or a regular blender.
Simmer the sauce for about 30 minutes for the best flavor and texture. Cooking it too long can sometimes make the tomatoes taste bitter or overly acidic.
If your sauce tastes too acidic, add a small pinch of sugar to help balance the flavor.
Stir in some fresh basil at the end of cooking for a fresh burst of flavor.
Substitute white wine for the chicken broth if you prefer.