1. Add canola oil to a saucepan over medium-high heat.  Add onions and sauté onions until soft and translucent, about 5 minutes. Remove from pan and set aside.  Do not discard pan with oil
2. Meanwhile in food processor, blend tomatoes for about 30 seconds or until just smooth
3. Add the pureed tomatoes to the pot with the oil.  Add the cooked onions. Season with salt and pepper
4. Bring to a boil then lower heat and let simmer for approximately 45-60 minutes over medium-low heat, adding a few (whole or chopped) basil leaves after 45 minutes
5. Can be used immediately or put in individual containers to use at a later time. Leftovers can be frozen for up to 3 months

Classic Marinara is Christine & Carla Pallotta's choice for layering their 5-Cheese Lasagna.