Heat 1 Tbsp olive oil in a large skillet over medium heat for about one minute. Add onion, carrots, and celery, and saute for five minutes, stirring occasionally. Move onion mixture into the Crock-Pot.
Add another 1 Tbsp olive oil to the same skillet, then pour in the can of whole tomatoes. Stir in garlic, and saute the tomatoes and garlic over medium heat for about three minutes, breaking them up with a wooden spoon as you go. Pour the tomato-garlic mixture into the Crock-Pot.
Stir in broth, water, potatoes, green beans, corn, Cannellini beans, and seasoning, then cook your soup on low for seven hours.
Remove the bay leaf. Add in the red wine vinegar, stir in spinach until wilted, and serve.
Note: Don't be deterred by the number of ingredients here -- the recipe is very straightforward, and the list just looks long because it's very veggie!