6 ounces slab bacon, sliced ¼ inch thick, slices cut into ¼ inch pieces
4 ripe but firm Bosc pears, quartered, seeds removed
Kosher salt, freshly ground pepper
1 tablespoon white wine vinegar
1 tablespoon whole grain mustard
3 tablespoons plus 2 teaspoons walnut oil or olive oil
½ cup unsalted, roasted walnuts
Sliced chives (for serving)
Cook bacon in a large skillet over medium, stirring occasionally, until golden brown and crisp around edges, 10–12 minutes. Using a slotted spoon, transfer to paper towels to drain. Pour off all but 1 Tbsp. bacon fat from skillet.
Season pears with salt and pepper and cook in skillet with bacon fat over medium-high, turning occasionally, until golden brown and starting to soften (they should be slightly firm at cores), 5–7 minutes. Transfer to a platter; let cool.
Meanwhile, whisk vinegar, mustard, and 3 Tbsp. oil in a small bowl to combine; season dressing with salt and pepper. Toss walnuts with remaining 2 tsp. oil in another small bowl; season with salt. Drizzle dressing over pears and scatter walnuts and bacon on top. Just before serving, top with chives.
Do Ahead: Dish (without chives) can be made 3 hours ahead. Store tightly wrapped at room temperature.