Preheat the oven to 180°C (356°F).
Place the onions, tomatoes, green chilies, carrots, and bell peppers on a baking tray. For the garlic, cut off the top, drizzle with olive oil, wrap it in foil, and also place it on the tray.
Drizzle all the veggies with olive oil and sprinkle with salt. Roast in the oven for 60 minutes.
Transfer the roasted vegetables to a pot. Squeeze the roasted garlic cloves into the pot. Add basil, thyme, fennel seeds, and ground black pepper. Pour in the hot water, stir well, and let it simmer on low-medium heat for 20 minutes. (Note 1)
Use an immersion blender to blend the soup until creamy. (Note 2)
Stir in coconut milk and cook for another 10 minutes on low-medium heat, and adjust the salt, if necessary.
Serve hot, topped with a drizzle of coconut milk and croutons for crunch (optional). Enjoy!