Preheat your oven to 400°F (200°C).
Place your leftover roasted vegetables on a baking sheet lined with parchment paper.
Roast the vegetables in the preheated oven for about 15-20 minutes, or until they are heated through and slightly caramelized.
Transfer the roasted vegetables to a blender and add enough vegetable or chicken broth to cover them.
Blend the mixture until smooth, adding more broth as needed to achieve your desired consistency. (See Notes on Broth)
Pour the blended soup into a pot and heat it on the stove over medium heat until warmed through.
Season the soup with salt, pepper, and any herbs or spices you like, adjusting to taste.
Serve the soup hot, garnished with a drizzle of olive oil, a sprinkle of fresh herbs.