1. In a stock pot or ceramic pot heat the olive oil to medium heat. Once hot add the onions a pinch or 2 of salt to allow them to sweat for 2 minutes.
2. Add the tomato puree, diced tomatoes, vegetable stock, and season well with salt and pepper (about 2 teaspoons each to start). Bring the tomato soup to a simmer and cover the pot and turn to low and let this cook for 25 minutes.
3. After the soup has cooked taste and adjust the seasoning if necessary. Turn the heat off and keep the soup covered and let it sit for about 15 minutes and then serve.