Heat the olive oil in a large saucepan. Add the onion, season with salt and pepper, and cook, stirring occasionally, until translucent, about 5 minutes.

Add the carrots, season with salt and pepper, and cook, stirring occasionally, about 2 minutes.

Add the celery. Season again with salt and pepper and cook an additional 5 minutes.

Add the broth, potatoes, lemon juice, and cilantro. Let the soup come to a boil, then reduce the heat to low and gently simmer, uncovered, until the potatoes can be easily pierced with a fork, about 15 to 25 minutes. Taste and season with additional salt and pepper as needed.

Garnish with dill and serve.