Preheat oven to 425°F. Wash brussels sprouts and trim stems. Slice in half lengthwise.
In a medium mixing bowl, toss brussels sprout halves and any leaves that fell off with olive oil, salt and pepper. Pour onto a baking sheet in a single layer, and roast for 20-25 minutes or until brussels sprouts are caramelized and leaves are crispy.
Meanwhile, make the sauce: heat olive oil over medium heat in a small saucepan. Add garlic and ginger, cook for 1 minute or until fragrant. Add cornstarch and stir to coat garlic and ginger.
Add in rice vinegar, soy sauce, sesame oil, and dried chiles. Bring to a boil, and turn heat to low to simmer until thickened. Add more sriracha and sugar to taste. Add more or less water as needed until desired consistency is reached.
To serve: toss brussels sprouts with kung pao sauce and place on a serving platter. Top with chopped peanuts, green onions, and cilantro.