Preheat the oven to 425° F.
On a large sheet pan, toss the chicken with 1 tablespoon tamari and 1 tablespoon orange juice. Season with pepper. Sprinkle the cornstarch (or arrowroot powder) over the chicken, lightly toss, and drizzle with olive oil. Bake for 15 minutes.
To make the sauce, in a bowl, whisk together ⅓ cup tamari, 2 tablespoons orange juice, honey, chili paste, garlic, and ginger.
When the chicken is ready, pour two-thirds of the sauce over the chicken. Toss and bake for another 5 minutes, or until cooked through. Switch the oven to broil and broil for 1-2 minutes, until the chicken chars on the edges. If desired, spoon over the remaining sauce.
Meanwhile, make the yum yum sauce by combining all ingredients in a bowl. Taste and season with cayenne and salt.
To assemble, add the rice to bowls, top with cucumber, avocado, chicken, kimchi, green onions, and a big handful of fried wontons. Spoon over the yum yum sauce.
