Ingredients

  • 2 pounds small white boiling potatoes (about 2 inches in diameter)
  • 1 medium onion
  • 1 firm-ripe California avocado
  • 1 bunch fresh dill
  • 3 cups cooked lobster meat (about 1 pound)
  • 3/4 cup mayonnaise
  • 1/2 cup sour cream
  • 2 tablespoons drained bottled horseradish, or to taste
  • 1 tablespoon red-wine vinegar
  • 1 bunch watercress

Method

  • In a 5-quart kettle cover potatoes with salted cold water by 2 inches and simmer until just tender, 15 to 20 minutes.
  • Drain potatoes in a colander and, while still warm, cut into quarters.
  • Transfer potatoes to a large bowl and cool.
  • Finely chop onion.
  • Halve, pit, and peel avocado and cut into 1/2-inch pieces.
  • Chop enough dill leaves to measure 1/2 cup.
  • Cut lobster into 1/2-inch pieces and add to potatoes with onion, avocado, and dill.
  • In a small bowl whisk together mayonnaise, sour cream, horseradish, vinegar, and salt and pepper to taste and pour over salad.
  • Gently toss salad until combined well and season with salt and pepper.
  • Chill salad, covered, at least 1 hour and up to 1 day.