Mix the chicken and marinade ingredients in a bowl and let it sit for 30-60 minutes.
Drain any excess liquid and mix the chicken with the cornstarch to coat all sides of each strip.
Heat the oil in a skillet (or Dutch oven) to 375°F.
Place the chicken in the skillet in a single layer, being careful not to overcrowd the pan (you'll need to cook in 2 batches).
Fry for about 3-4 minutes per side, until golden brown.
Remove from the pan and place on paper towels or a rack to allow excess oil to drain.
Serve the chicken in a bowl over rice and topped with the sauce (below) and the toppings. Serve hot.
Karaage sauce:
Combine all the ingredients and simmer on medium low heat for about 5 minutes, until slightly reduced and thickened (it won't be super thick - it will thicken as it starts to cool - don't overcook).
Serve over rice bowls.
Notes
The longer the chicken marinates, the more flavor it has. Marinade a minimum of 30 minutes and maximum of 8 hours.
Shake of excess cornstarch before frying.
Do not overcrowd the pan - there should be space between each piece. Overcrowding the pan can cause the temperature to drop and the chicken will come out soggy instead of crispy.
If thekaraage is not crispy, it could mean that your oil wasn't hot enough and/or you crowded the pan when frying the chicken. It also loses it's crispiness if it is not served right away.
Use an instant read thermometer to ensure the oil is the correct temperature before adding the chicken. Make sure the temp never drops below about 325°F, but try to keep it at at least 350°F while frying (it starts at 375°F but will drop when the chicken is added).