Start with sweating onions and garlic in the oil till soft.
Add tomato paste, salt, and pepper. Cook for another few minutes then add all cans of tomatoes squeeze/crush the whole peeled then continue to cook on med low for 45 min to an hour.
Check for seasoning then add basil and parsley for the last 10 min of cook time.
Optional: If San Marzano tomatoes are unavailable, add a touch of sugar.