Whisk the garlic, sake, salt, and black pepper together in a medium bowl until the salt is fully dissolved.
5 grams garlic, 2 tablespoons sake, 1/2 teaspoon salt, 1/2 teaspoon black pepper
Trim any excess fat or tough connective tissue of the chicken.
400 grams skin-on boneless chicken thighs
Look for natural partitions in the meat with the skin-side down and follow them with a sharp knife to slice the chicken into 1.5-inch strips (4cm).
Next, you want to cut the strips into pieces of chicken that are roughly the volume of a golf ball. This will mean that thinner areas will need to be cut longer while thicker areas should be shorter.
Add the cut chicken to the marinade and stir to coat each piece evenly. Cover and refrigerate for at least 1 hour or preferably overnight.
When you're ready to fry your chicken karaage, add 1-2 inches of oil to a heavy pot with high sides and preheat to 340°F (170°C). Prepare a cooling rack by lining it with a few paper towels.
Put the potato starch in a bowl, and then roll each piece of chicken in the starch to coat it in an even layer. Next, use your fingers to squeeze the chicken into a ball and lower each piece into the preheated oil. I recommend frying the Karaage in two batches.
50 grams potato starch
Once the coating on the chicken has set, flip the pieces over to cook them evenly.
How long the chicken takes to cook will depend on how large the pieces are, but they should take about 5 minutes to cook through. They should read an internal temperature of 160°F (71°C) when they're cooked. Transfer the chicken as they cook to the prepared rack to drain.
Serve the Shio Karaage immediately with a few wedges of lemon.