| 2 tbsp olive oil, plus a little extra (according to taste) | 3 garlic cloves, finely chopped | |
| 2 onions, finely chopped | 2 tbsp tomato puree or tomato paste | |
| sea salt and freshly ground black pepper | 2 x 14 oz (400 g) cans cannellini beans | |
| 1 tbsp finely chopped rosemary leaves | 4 cups hot chicken stock | |
| a few sage leaves, finely chopped | 2 lb (2.5 kg) potatoes, cut into ½ in (1 cm) cubes | |
| 4 celery ribs, finely chopped |
Heat the oil in a large saucepan, add the onions, and cook over low heat for 6-8 minutes or until soft. Season well with salt and freshly ground black pepper, then stir in the rosemary, sage, celery, and garlic and cook over very low heat, stirring occasionally, for 10 minutes.
Stir through the tomato puree and beans, add a little more olive oil if you wish, and cook gently for 5 minutes. Pour in the stock, bring to a boil, then add the potatoes and simmer gently for 15 minutes or until cooked. Taste and season again with salt and freshly ground black pepper if needed. Cool.
Transfer to a freezer-proof container. Seal and freeze for up to 3 months.
To serve, defrost in the refrigerator overnight, then transfer to a saucepan and simmer until piping hot. Add a little hot stock if the soup is too thick.