- 2 tbs olive oil
- 1 large onion, chopped
- 2 cloves garlic, finely chopped
- 2 celery sticks, finely sliced
- 2 medium white potatoes, peeled and cubed
- 1 1/2L vegetable stock
- 450 g (3 cups) fresh or frozen peas, thawed if frozen
- 200 g (8 cups) watercress, washed
- 1/2 lemon, juiced
- 50 g (1/2 cup) Parmesan, shaved
- Freshly ground black pepper
Heat the olive oil in a saucepan set over a medium heat until hot.
Add the onion, garlic, celery, and a generous pinch of salt, sweating until softened, about 5-6 minutes.
Add the potato and stock, and continue to cook for about 15 minutes, stirring occasionally, until the potato is soft. Remove about one-third of the onion, celery, and potatoes to a bowl, setting aside until needed.
Stir about two-thirds of the peas and about two-thirds of the watercress into the soup. Bring to a steady simmer, cooking until the peas are tender, about 4-5 minutes.
Remove the pan from the heat and purée with an immersion blender, keeping some of the texture to the soup; you can also do this step in a food processor or a blender.
Return the soup to a very gentle simmer and season to taste with lemon juice, salt, and pepper.
Divide between bowls and top with the reserved vegetable mixture, the remaining peas and watercress, and some shaved Parmesan.