In a large pot, heat the olive oil over medium heat, then fry the onion until translucent. 2-3 minutes.
Add the carrots, celery, green beans, potato and butternut, and fry until they begin sweating, about 5 minutes. Season to taste.
Add the water, stock cubes and tomato paste. Give it a good stir.
Simmer on medium heat until all the vegetables are soft, 15-20 minutes, depending on how big or small you’ve chopped your vegetables.
Turn the heat down to low, add the butter beans and simmer for 15 minutes.
Serve with fresh bread and a good squeeze of lemon juice.