Ingredients:
- 10 oz. watercress, stems removed
- 3 tbsp. unsalted butter
- 1 lb. leeks, white and light-green parts handiest, halved, rinsed, and thinly sliced
- 1 tidy yellow onion, finely chopped
- Kosher salt, to taste
- 4 cups chicken stock (or vegetable stock)
- 3 cups heavy cream
- Freshly ground white pepper, to taste
- Juice of 1 lemon
- 2 tbsp. caviar, corresponding to osetra (no longer mandatory)