Heat oil in large soup pot over medium heat. Add leek, garlic and salt and sauté until soft, about 3-4 minutes. Add carrots and green beans and cook for another 3 minutes.
Add vegetable stock and bring to a boil. Reduce to a simmer and add tomatoes, and mushrooms. Cook for 15 minutes, simmering on low heat. Add asparagus and half of the basil and parsley and cook for 2 minutes.
Remove from heat and distribute into each serving bowl, squeezing a generous amount of fresh lemon juice over each bowl and garnishing with the remaining basil and parsley.