Mix together the vinaigrette ingredients in a small bowl with half the chopped cilantro and set aside.
Wash and pat dry the Brussels sprouts. Trim away the stem and remove any loose leaves. Cut in half lengthwise through the stem and place in a bowl.
Heat the oil in a large, oven-proof skillet over medium-high. Add the sprouts, cut side down, in a single layer and fry until the bottoms are slightly browned, about 2-3 minutes. Shake the pan every once in a while. Then transfer to the oven and roast until the sprouts are tender and the tops start to brown, about 5-8 minutes.
Transfer to a bowl and dress with the vinaigrette. Garnish with the remaining cilantro and serve.
Recipe by Oishii Rasoi at https://www.oishiirasoi.com/roasted-brussels-sprouts-with-fish-sauce-vinaigrette/