For sprouts, preheat oven to 400 °F. Heat about 2 tablespoons oil in two oven safe skillets over medium heat. Add sprouts, cut-side down to the skillets. You’ll need two to hold all the sprouts. Don’t pile them in one skillet.
After bottoms of sprouts begin to brown, about five minutes, transfer skillets to oven to finish roasting for 10-15 minutes until they are really crispy on the bottom and around the edges. Don’t stir them or touch them.
For sauce, combine fish sauce, water, vinegar, lime, sugar, garlic, and chiles in a bowl. Taste for salt. if it’s too salty, add more water. Right before serving, combine this base with cilantro and mint.
Drizzle roasted sprouts with the vinaigrette and serve warm or at room temperature.