Combine first 8 ingredients in a jar; cover tightly, and shake vigorously. Chill thoroughly.
Place 1 cup spinach on each of 2 salad plates. Arrange pear and tomato evenly over spinach. Sprinkle walnuts evenly over each salad.
Shake vinegar mixture, and pour into a small saucepan. Cook over medium heat until thoroughly heated; spoon warm vinegar mixture over salads. Serve immediately.