Ingredients

• 
  1 1/2 pounds Brussels sprouts, trimmed and thinly sliced (about 9 cups)
• 
  2 medium sweet potatoes (about 1 lb. total), peeled and cut into 1/2-inch cubes (about 2 3/4 cups)
• 
  1 medium onion, sliced (about 2 1/4 cups)
• 
  1/4 cup extra-virgin olive oil, plus more for baking sheets
• 
  1/4 teaspoon crushed red pepper flakes
• 
  Salt
• 
  2 tablespoons cider vinegar
• 
  2 teaspoons Dijon mustard
• 
  1 teaspoon honey

Preparation