In a medium bowl, combine the chicken thighs, 2 tablespoons of oyster sauce, dry Sherry, and 1 teaspoon sesame oil. Mix until the chicken is evenly coated, and then set aside to marinate at room temp while you prepare the sauce.

Combine 2 tablespoons vegetable oil and the garlic in a small, heavy saucepan over medium-low heat. When the garlic begins to sizzle, cook, stirring, until it turns golden brown, 1 to 2 minutes.

Add the tomato paste and cook, stirring often, until the paste turns a deeper color, about 2 minutes.

Stir in 3 tablespoons water, the brown sugar, vinegar, soy sauce, remaining 3 tablespoons oyster sauce, remaining 2 teaspoons sesame oil, and the crushed red pepper. Increase heat to medium and cook, stirring occasionally until the mixture thickens to the consistency of warm honey (about 2-3 minutes). Remove the pan from the heat and set aside.

In a large cast iron skillet or Dutch oven Heat 2 inches of vegetable oil 0ver medium-high heat to 375℉. Line a large bowl with paper towels.

Beat the eggs in a wide, shallow dish. Place the entire packet of Lucky Tempura mix in a second shallow dish. Place one third of the chicken in the egg mixture and toss until fully coated, allowing excess to drip back onto the dish. Transfer chicken to the cornstarch; toss until each piece is fully coated.

When the oil is at temp, carefully slip the chicken into the hot oil. Fry for 5-6 minutes, until the chicken is golden brown and cooked through. Use a spider or slotted spoon to transfer the chicken to the bowl, and lightly season with salt. Repeat with remaining chicken, ensuring the oil returns to 375℉ degrees before frying each new batch.

Remove the paper towel from the bowl of fried chicken and drizzle the sauce over the chicken pieces. Add half of the sesame seeds and toss until the chicken is evenly coated. Serve the chicken over steamed rice, garnished with the sliced scallions and remaining sesame seeds.