Preheat the oven’s broiler. Arrange pear slices in a single layer on a baking sheet. Broil until nicely browned, 3 to 5 minutes. Set aside to cool.

Pour port wine into a saucepan. Bring to a boil, and cook until the wine is reduced by 1/2. Remove from the heat and cool. Pour cooled wine into a blender or food processor, and add the shallots, garlic, mustard, and vinegar. Puree until smooth.

Divide salad greens evenly between four serving plates. Arrange some of the broiled pear slices over each pile of greens. Sprinkle with Gorgonzola cheese. Drizzle dressing over each plate, then sprinkle with walnuts.