In a large pot or Dutch oven, bring 6 cups of chicken or vegetable broth to a gentle boil over medium-high heat. Add the cubed potatoes and reduce to medium-low. Cook for 15 minutes until tender.

Heat 2 tablespoons of olive oil in a skillet over medium heat. Add the minced onion and grated carrot, sauté for about 10 minutes until onions are translucent.

Add the sautéed mixture, cubed zucchini, and chopped spinach to the pot. Stir and let simmer for 5 to 7 minutes until the spinach wilts.

Season with salt and pepper, then stir in lemon juice, cubed hard-boiled eggs, and fresh herbs. Cook for 2 minutes to meld flavors.

Ladle soup into bowls and serve topped with sour cream.