1. Cut the pears into thin slices and toss with 1 tablespoon of the lime juice in a medium bowl. Cut the grapes into halves.
2. Tear the lettuce into bite-size pieces and use to line 8 individual salad bowls. Arrange the pears, grapes and walnuts over the lettuce. Cover the bowls and chill for 1 hour.
3. In a medium bowl, combine the remaining 3 tablespoon lime juice, the honey, poppy seeds, onion, lime zest, salt and mace. Gradually add the vegetable oil, beating continually with an electric mixer set at high speed. Beat until the mixture is thick.
4. Drizzle equal portions of the dressing over the salads and serve.
Tip: Storing Poppy Seeds
Poppy seeds can sometimes develop an off flavor after just a few months. If you use them only occasionally, keep them fresh and tasty by storing in a plastic resealable bag in the freezer.