Preheat the oven to 350 degrees F. On a small, rimmed baking sheet, roast the peanuts until golden, about 5 minutes. Set aside to cool. In a food processor, add the lime zest along with the cooled peanuts, turbinado sugar, and salt. Pulse until the peanuts are roughly chopped, about five 1-second pulses.
Trim the lower third from the stem end of each Brussels sprout and discard. Separate the loose outer leaves from each Brussels sprout and place them in a medium bowl. Halve the trimmed sprouts lengthwise and then thinly slice crosswise using a mandolin. Add the sliced Brussels sprouts to the bowl with the leaves.
In a small bowl, whisk together the lime juice, kimchi juice, Sriracha, and salt. Pour this mixture over the Brussels sprouts and use your hands to toss and massage until the sprouts start to soften, 15 to 30 seconds. Add the sliced kimchi, scallions, and all but 1 tablespoon of the peanut-lime mixture. Toss to combine, transfer to a serving bowl, and sprinkle with the remaining peanut-lime mixture before serving.