How to Make It
In a small frying pan, toast the nuts over moderately low heat, stirring frequently, until golden brown, about 5 minutes. Or toast them in a 350° oven for 5 to 10 minutes.
Put the potato in a medium pot of salted water. Bring to a boil and simmer until tender, about 10 minutes. Drain and set aside.
Meanwhile, in a large glass or stainless-steel bowl, combine one third of the blue cheese with the vinegar, salt, and pepper. Mix thoroughly and then gradually whisk in the oil. Reserve 2 tablespoons of the dressing. Add the romaine to the rest of the dressing and toss. Transfer to a platter or salad bowl.
Toss the watercress with the reserved dressing. Arrange the remaining blue cheese, the watercress, walnuts, potato, onions, avocado, and pear slices on top of the lettuce.