1. Sauté the onion, carrots, celery, and mushrooms (if using) in a large saucepan over medium heat until the onion turns translucent and starts to brown, about 8 minutes. Add water 1 to 2 tablespoons at a time to keep the vegetables from sticking.
2. Add the vegetable broth, potatoes, dill, basil (if using), and thyme. Cover and cook until the potatoes are tender, about 20 minutes.
3. Add the plant-based cheese sauce, season with sea salt and black pepper to taste, and cook for another 5 minutes.
4. To serve, ladle the soup into bowls and garnish each serving with additional fresh dill.
1. You can substitute the plant-based cheese sauce with 2 cups of unsweetened plant-based milk mixed with 2 tablespoons of arrowroot powder.