Start by draining the soaked cannellini beans, then fill a large pot with fresh water and add the beans. Bring the pot to a rolling boil for 3-4 minutes; then drain the beans again and set them aside.

In a medium pot, heat the olive oil over medium-high heat. Add the minced onion and chopped garlic, cooking for about 5-7 minutes until the onion turns translucent and golden.

Add the prepared beans to the pot along with 1.5 liters of water, or 1 liter of water and 500 ml of vegetable stock. Stir and bring to a boil.

Reduce heat to medium-low, cover the pot slightly ajar, and let simmer for approximately 2 hours until beans are tender and creamy.

Stir in chopped celery and sliced carrot, season with salt and pepper. Continue simmering for another 30 minutes.

Add the zest and juice of a fresh lemon, stir well and let simmer gently for an additional 2 minutes.

Ladle the soup into bowls and sprinkle with additional pepper or lemon juice if desired. Serve warm with crusty bread.