Marinate the chicken: Combine the chicken, kosher salt, tamari, sesame oil, and cornstarch in a bowl. Mix to coat and let sit for 15-20 minutes while you prepare the other ingredients.
Make the sauce: Whisk together tamari, rice vinegar, sesame oil, sriracha, chicken broth, honey, and cornstarch in a small bowl. Heat vegetable oil in a saucepan over medium heat. Add ginger and garlic, cooking until fragrant (about 1-2 minutes). Pour in the sauce mixture and simmer, whisking, until thickened (roughly 2 minutes).
Prepare for frying: In a large bowl, whisk together cornstarch, gluten-free flour, baking powder, and a pinch of salt. Preheat your frying oil in a heavy-bottomed pot to 350°F.
Bread and fry the chicken: Coat the marinated chicken pieces evenly in the flour mixture, shaking off excess. Gently lower chicken pieces into the oil and fry, stirring occasionally, until golden brown (about 3 minutes). Drain on paper towels.
Toss with sauce: Transfer the fried chicken into the saucepan with your prepared sesame sauce. Gently toss until all pieces are evenly coated.
Assemble and serve: Serve the chicken over cooked rice and garnish with sesame seeds and scallions for a restaurant-quality presentation.