Drain the soaked beans and fill a large cooking pot halfway with fresh water. Add the beans and bring to a vigorous boil over high heat. Cook for 3-4 minutes, then drain.

In a medium-sized pot, heat the extra virgin olive oil over medium-high heat. Once hot, add the minced onion and chopped garlic. Sauté until softened and golden.

Add the drained beans back into the pot along with 1.5 liters of water, or use 1 liter of water with the addition of vegetable stock. Bring to a boil, reduce heat to medium-low, cover slightly ajar, and simmer for about 2 hours.

After beans are fully cooked, add finely chopped celery and carrot. Season with salt and pepper, and stir occasionally until the soup thickens. Stir in lemon juice and zest just before serving and cook for another 2 minutes.

For Instant Pot, use sauté function for olive oil, onion, and garlic, then add other ingredients with 1.5 liters of water or stock. Cook on manual for 20 minutes and let sit for 5-10 minutes before releasing steam. Finish with lemon juice and zest.

For Slow Cooker, sauté onion and garlic in olive oil beforehand. Combine with remaining ingredients (exclude lemon juice and zest and 1.5 liters of water). Cook on low for 8 hours or high for 4 hours, then add lemon juice and zest for last 5 minutes.