Cut chicken thighs into bite-sized pieces and place in a bowl. Mix the 1/2 cup cornstarch, flour, salt, and pepper. Beat the egg in a small bowl with the 1 tbs oil. Mix in the cornstarch mixture. Add the cornstarch/egg mixture to the chicken in the bowl. Coat well.

Heat enough oil to deep fry in a large, deep skillet or wok. Heat oil to 375 degrees. Fry chicken in batches so there is plenty of room around the chicken. Maybe 6-8 pieces at a time. Fry on each side 5-7 minutes or until crisp and beginning to brown. Drain with slotted spoon and place on a paper towel-lined plate. Repeat until all chicken is cooked.

Mix the soy sauce, rice vinegar, sugar and orange zest in a small bowl. Set aside.

Remove oil from wok and wipe out. Heat over high heat for about 10 seconds and add the other 1 tbs of oil. Toss in the minced garlic and ginger and stir fry until very aromatic--maybe 15 seconds. Put the broccoli in and stir fry for 15 seconds. Add the green onion and the pepper flakes and stir fry for 10 seconds. Stir the sauce in the bowl and add it to the wok. Bring sauce to boil. Add the mirin/saki and the sesame oil. Mix the 1/4 cup water and 1 tbs cornstarch and add to the boiling sauce, stirring constantly until sauce is thickened and bubbling. Add cooked chicken coating well with sauce.

Serve immediately over rice.