Preheat the oven to 425°F . Arrange the diced tomatoes, onion and garlic on a baking sheet then toss (or spray) with high heat oil. Sprinkle with salt and pepper then roast in the oven for 35 minutes. Set aside to cool for at least 5 minutes.
Transfer roasted vegetables into a blender with 1 cup of vegetable broth, oregano and basil leaves. Pulse until a thick and chunky texture is achieved (or smoother, if desired). Pour into a large pot and add more broth as needed. Alternatively, you could use an immersion blender and blend everything in the pot.
Warm the pot over medium heat until the soup is heated through. Add more salt to taste, if desired. Serve warm garnished with chopped basil and a side of grilled cheese, and enjoy!
Notes
Nutrition Facts are for 1 cup of soup (or 1/4th of recipe). They are an estimate and will vary depending on specific brands you choose.