I'm not a fan of measuring stuff, I'm more of an "eyeball it" chef, so this is more or less approximately what I used.
Also, this may be a traditional Amatsu dish, but it is not a traditional Karaage (afaik). This is my own recipe and I'm not Japanese so don't hate me =P.
You will need:
Meat:
- 500g - 700g chicken thighs (it doesn't have to be exact)
- 2.5 tbsp soy sauce
- 2.5 tbsp sake or Chinese cooking wine
- 1 tsp sesame oil
- 1/4 apple, grated
- salt and pepper
- chili powder, optional
- frying oil
- corn starch or flour
Sauce:
- Japanese mayonnaise
- green onion
- sesame oil
- your favourite hot sauce (avoid using overly acidic ones like Tabasco)
1. Prepare your awkwardly rectangular Peco meat/chicken thighs. I guess that's what you get for shopping at Loblaws :V.

2. Debone the chicken thighs and cut into bite sized pieces. You can remove the skin, but my parents like it skin on so I did half and half. I later realized about halfway through frying that you can't really differentiate which is which after you fry it, so pick one or the other. If you keep the skin on, though, be sure to thoroughly remove any remaining feathers because as you can see above, sometimes the butcher does a terrible job at cleaning it.

3. Place the chicken thighs into a bowl, and add the marinating ingredients. Season with salt and pepper.

I added some chili powder after this picture, but it's up to you. Just don't add too much as you don't want to overpower the other flavours. Mix well and store in the fridge for at least 2 hours, or if you're like me and decided to make this on a whim at 12:30am, leave it overnight.

4. When ready to cook, heat the oil to about 325°F to 350°F. I say about because I don't really know what the temperature was when I fried it, but a good way to check if the oil is ready is to place a wooden chopstick into the oil. If bubbles start to form around it at a rate that's not too fast, it's ready.

5. Place the chicken onto a plate/tray of corn starch or flour and toss to coat. I use corn starch because I find it adheres better and makes it crispier than flour, but it doesn't really matter. Be sure to shake off any excess before frying.

6. Fry the chicken for about 4 minutes, or until they turn golden brown. Turn them over every now and then to prevent them from getting too dark. We still need to double fry them, so fry slowly.

Remove from the oil and place on a paper towel to remove the excess oil and cool for about 2-3 minutes.

8. Heat the oil a little hotter (iunno, 375°F? 400? I didn't measure x_x) and fry the chicken again for about 30 seconds, turning them over frequently to fry the outside evenly.

Remove the excess oil by placing on a paper towel again.
9. Make a simple sauce using Japanese mayonnaise, lots of fresh, finely chopped green onions, and a small amount of sesame oil. You can blend it up in a food processor if you wish, but I like the crisp flavour the pieces of green onions give. Don't add too much sesame oil, about 1/3 tsp is enough. Sesame oil easily overpowers other flavours, so be careful. Then add a dash of your favourite hot sauce. Don't use overly acidic hot sauces as they will make the flavour kinda... meh. I used a homemade chili sauce made from toasted chili peppers and some other stuff I can't tell you or else I'd have to kill you.
Then plate it up however you want and serve immediately.
