Heat butter or olive oil in a soup pot over medium heat. Sauté onion, carrots, leek, and celery for 5 minutes.
Add garlic, zucchini, green beans, thyme, and ⅔ parsley; sauté for 3 more minutes.
Stir in cauliflower, broth, bay leaves, salt, and pepper. Bring to a boil, then simmer for 15 minutes with the lid on.
Remove half the soup and bay leaves. Blend until smooth and return it to the pot.
Add kale and simmer for 1 minute until softened.
Stir in a lemon juice and olive oil mixture before serving. Garnish with parsley and adjust seasoning to taste.