2-3fresh thyme sprigs, or 1/2 teaspoon dried thyme
Preheat oven to 375⁰ F.
Place eggplant in a colander, sprinkle with salt to remove any bitter taste. Cover the colander with a dish towel or paper towel then place a heavy object on top of it and place it in the sink for about 15 minutes. Dry the eggplant with a dish towel or paper towel, and set aside.
On a parchment-lined baking sheet, arrange plum tomatoes, bell peppers, zucchini, eggplant, and onions on a baking sheet in a single layer. Drizzle with the olive oil and sea salt. Bake for 35-40 minutes, until eggplant and bell peppers have a slight char on their skins. Once done, remove from oven and set aside.
In a large pot, add vegetable broth, water, and roasted vegetables. Cook over medium heat for about 15 minutes, stirring occasionally. When done, remove soup from heat and place in a blender. Puree well, and serve. If desired, garnish with thyme.