Cook bacon in large skillet, stirring occasionally, until golden brown and crisp around edges, about 10-12 minutes.
Using a slotted spoon, transfer bacon to paper towels to drain. Pour off all but 1 Tbls. of the bacon fat from the skillet.
Season pears with salt & pepper. Cook in skillet over medium-high heat, turning occasionally until golden brown and starting to soften (core should remain firm), 5-7 minutes. Transfer to a platter to cool.
While pears cool, whisk vinegar, mustard, and 3 Tbls. of the oil in a small bowl to combine, season with salt & pepper.
Toss walnuts with remaining 2 tsp. of oil in a separate small bowl and season with salt.
Drizzle dressing over pears and scatter the walnuts and bacon on top. Just before serving, top with the chives.