Preheat oven to 400 degrees Fahrenheit (200 degrees Celsius).

Divide sliced veggies between two greased baking sheets. Spray vegetables liberally with cooking spray and sprinkle with salt.

Roast for 45-60 minutes, stirring once or twice, until edges of vegetables start to brown.

Add contents of one baking sheet to a large pot with eight cups of water and spices. Cook until heated through; blend with immersion blender. If the soup seems too thick, add one to two cups water.

Add remaining roasted vegetables and simmer for about 15 minutes until hot.