Watercress Salad

Name: Watercress Salad
Ingredients: 5 tablespoons vegetable oil; 2 leeks, white parts only, sliced into very thin rings; Salt and freshly ground pepper; 1 1/2 tablespoons soy sauce; 1 tablespoon sherry vinegar; 1 tablespoon minced shallots; 1 1/2 tablespoons hazelnut, walnut or olive oil; 1 bunch watercress (6 ounces), thick stems discarded; 2 cups finely shredded red cabbage; 1/4 cup finely chopped chives, for garnish