Heat your oven to 400 degrees, toss the Brussel sprouts in olive oil and spread on a sheet pan, season with salt and pepper. Roast until the sides facedown on the pan begin to blacken, about 15 minutes.
While the sprouts are roasting, add 2 tbsp to a large skillet or wok and saute the onion and pancetta for 3 minutes over medium heat. Add the light green and white portions of the scallions, ginger, and garlic and continue to saute until fragrant, about 3 more minutes.