Transfer the soup to a high-powered blender and add the spinach, mint, basil, parsley, the remaining 1 teaspoon kosher salt, black pepper to taste, lemon juice, and coconut milk (if using). Depending on the size of your blender, you may need to do this in batches. Remove the blender cap to prevent trapping the steam inside the blender and cover the hole with a dish towel. Blend the soup until it is completely smooth and thick. If the soup is too thick for your liking, add more broth or water as needed to thin out. Season to taste with salt/pepper. If desired, garnish with additional fresh herbs and cucumber ribbons, black sesame seeds, vegan yogurt, and toasted pine nuts.