Combine the pear, Champagne vinegar, shallots, sugar, rosemary and black pepper in a skillet and bring to a simmer. Reduce the heat to low, cover, and simmer until the pears are tender, about 6 minutes. Remove from the heat and transfer to a blender or food processor.
Add the mustard, soy sauce, kosher salt, and green onions, and puree on high speed. With the motor running, add the oil in a thin stream and process until emulsified. Remove from the blender and refrigerate in an airtight container until ready to serve. (The vinaigrette will keep for up to 1 week refrigerated.)
Yield: 1 generous cup