In a pot heat the olive oil and add the onions.Saute until transparent.
Add garlic,salt and pepper.
Add the veggies and saute for about a minute.
Add the crushed tomatoes,oregano,salt and bring to a boil.
Reduce the heat,cover and cook until veggies are tender.
Add a little water if too thick.Check the seasonings.
Puree the sauce in a blender once its cool.
Transfer into a jar to be used in your pasta,soups etc.It stays good for upto a week.