Bakso Ayam dengan Saus Asam Manis

Bahan-bahan (20 porsi)

• 1 lb ground chicken
• ½ onion ((4 oz, 113 g))
• 1 large egg (50 g w/o shell)
• 3 Tbsp panko (Japanese breadcrumbs)
• 1 Tbsp potato starch or cornstarch
• 1 Tbsp sake
• ½ tsp Diamond Crystal kosher salt
• ¼ tsp freshly ground black pepper
• water ((for steaming))
• 6 Tbsp ketchup
• 4 Tbsp mirin ((I use Takara Mirin))
• 4 Tbsp soy sauce
• 2 Tbsp rice vinegar (unseasoned)
• 2 Tbsp sugar
• 1 Tbsp sake ((I use Sho Chiku Bai Classic Junmai Sake))
• 1 tsp potato starch or cornstarch ((for thickening))