Preheat oven to 425F.
Peel and cube 9 cups sweet potatoes into even-sized pieces.
Toss cubes with 2 Tbsp neutral oil on greased baking sheet and spread in single layer.
Roast on top rack for 12-15 minutes, flipping halfway through, until edges are crispy but centers aren't mushy.
While roasting, whisk together 1/3 cup miso paste, 1/4 cup maple syrup, 1 1/2 Tbsp coconut aminos, 1 Tbsp rice vinegar, and 1/4 cup water until smooth.
Add 3/4 tsp ground ginger and 1 Tbsp chili crisp if using.
Let sweet potatoes cool 5 minutes, then toss with glaze to coat.
Return to baking sheet and roast 5 more minutes to caramelize glaze.
Garnish with sesame seeds if desired.