Set the Anova Sous Vide Precision Cooker to 183ºF (83ºC).
Combine the Brussels sprouts, olive oil, and salt in a large zipper lock or vacuum seal bag. Seal the bag using the water immersion technique or a vacuum sealer on the dry setting.
Place the bag in the water bath and set the timer for 40 minutes. If using a zipper lock bag, you may need to weigh down the bag to keep the Brussels sprouts submerged.
Meanwhile, prepare the vinaigrette: Combine the fish sauce, water, sugar, rice vinegar, lime juice, chiles, and garlic in a small bowl. Stir to dissolve the sugar.
When the timer goes off, remove the bag from the water bath and transfer the Brussels sprouts to an aluminum foil-lined baking sheet. Heat broiler to high.
Broil the Brussels sprouts, stirring occasionally, until the sprouts are browned and slightly charred, about 5 minutes.
Transfer the Brussels sprouts to a medium bowl and toss with the vinaigrette to taste. (You may not need to use all of the vinaigrette.) Sprinkle mint and cilantro over the sprouts. Serve.
