Heat the oil in a medium skillet over medium heat. Add the vegetables, stir, and cover. Cook for 10 minute or until mostly soft.
Remove lid and stir in the tomatoes. Bring to a simmer, reduce heat to medium low and place the lid so it's mostly covering the pot but not a tight seal. This will let some steam escape but will protect your cooktop from splatters. Simmer for 20-25 minutes or until everything is soft.
Puree with an immersion blender or in a regular blender. Season to taste with additional salt as needed.
Serve with 1 pound of cooked pasta and Parmesan cheese, if desired.
