Basil-Flecked Potato Soup with Celery Leaves

This was just going to be a potato-leek soup, but some surprise basil and celery leaves from my sister's garden ended up in the mix, yielding a smooth green potage with an unexpected flavor. The soup is deepened by making a stock from the trimmings while you work--and really, is there anything more satisfying than making stock out of vegetable trimmings before you throw them in the compost, having fully used them up?

4 medium Yukon Gold potatoes
1 carrot
3 leeks
1/2 cup packed chopped basil
1/3 cup packed chopped celery leaves
3 tablespoons olive oil
1/2 teaspoon smoked Spanish paprika
1 teaspoon salt
pepper
Juice of 1/2 a lemon

Cover trimmings (carrot top, green part of leeks, celery leaf stems, basil stems, and any other scraps you generate) with water in a medium-sized saucepan, bring to a boil, and simmer while you dice the white part of the leeks, the carrot and the potatoes.

Heat the olive oil in a large stock pot. Add leeks and stir occasionally for about 5 minutes, then add in the carrot, potatoes, salt and paprika and stir over medium heat for about five minutes. Strain in enough stock to cover the vegetables, add the celery leaves and bring to a boil, then cover and simmer about 20-30 minutes, until potatoes are soft.

When the potatoes are tender, turn off heat and transfer soup to a blender. Add the basil and celery leaves and blend until smooth, adding more stock if the soup is too thick. Season with pepper to taste, adjust salt if necessary, and finish with lemon juice.