| 1 pound boiling potatoes, peeled and diced |
| 1 1/2 teaspoons kosher salt, more to taste |
| 2 leeks, white and light green parts, washed and diced |
| 1/3 pound cod fillet, diced |
| 1/3 cup chilled unsalted butter, diced |
| 2 tablespoons minced fresh chives |
| 4 teaspoons cognac or brandy (optional) |
| 1/4 teaspoon freshly ground black pepper |