For the sauce: Heat the sesame oil in a large saute pan over medium heat. Add the ginger-garlic paste and cook until fragrant, 1 to 2 minutes. Raise the heat to medium-high and add the chicken stock, soy sauce, orange juice, brown sugar, vinegar, mirin, orange zest and pepper flakes. Simmer for 8 to 10 minutes, stirring occasionally. Add the cornstarch slurry and stir until the sauce is thickened. Keep warm.
For the chicken: With a mallet or a heavy pan, pound the chicken to an even 1/4-inch thickness. Add the chicken to a large resealable bag along with the soy sauce and ginger-garlic paste. Seal the bag and leave the chicken to marinate at room temperature for 30 minutes.
Preheat the oven to 200 degrees F.
Beat the eggs in a wide, shallow bowl. In a large plate mix together the flour, granulated garlic and ground ginger. In another plate, mix together the panko and sesame seeds. Sprinkle all three dishes with salt and pepper. Dredge the chicken first in the flour, then in the egg and lastly in the panko.
Slick a large skillet with peanut oil and set over medium-high heat. In batches, fry the chicken until golden brown and cooked through, 3 to 4 minutes per side. As you go, keep cooked chicken warm in the oven on a wire rack set over a baking sheet.
Slice the chicken into thick strips and arrange on a serving platter. Drizzle chicken with the sauce and garnish with sesame seeds and scallions.
Pulse the garlic and ginger in a food processor. With the processor running, stream in the canola oil and process to a paste. (You'll need 4 tablespoons of the paste for the present recipe. Refrigerate remaining paste for up to a week.)