Preheat oven to 425°F | 218°C. Line a heavy sheet pan with a Silpat mat (or with aluminum foil sprayed with cooking spray) and set aside.
With a paring knife, remove the base off of each Brussels sprout and cut down the middle from stem end to flower.
In a medium bowl, whisk together oil, vinegar, honey and Gochujang paste. Add in Brussels sprouts and toss to coat.
Spread prepared Brussels sprouts evenly on prepared sheet pan. Season liberally with salt and pepper.
Roast Brussels sprouts in preheated oven 25-30 minutes (depending on how large your sprouts are), or until the sprouts are dark golden. (See note.)
Remove from oven. Sprinkle peanuts and cilantro evenly over roasted sprouts and then transfer everything to serving dish. Garnish with additional chopped cilantro and peanuts. Serve warm or at room temperature.
When spreading Brussels sprouts on the pan to put in the oven, I like to start them all with their cut side down, flipping them with a spatula halfway thru the cooking process.