1. To make dressing, mix together honey, vinegar, and mustard. Using a wisk, add oil in a slow stream and mix well. Stir in poppy seeds. This makes about a cup of dressing.
2. Using a serrated knife, cut, and peel the membranes from grapefruit. Section fruit and throw away the membranes.
3. Gently arrange spinach on individual plates. Top with sliced avocado and grapefruit sections. Drizzle 1 tablespoon dressing over each salad. Sprinkle with toasted pine nuts and gorgonzola, if desired.