Spicy Chicken Teriyaki Bowls

Make the chicken teriyaki : In a mixing bowl, combine soy sauce, sugars, garlic, ginger, black pepper, and cayenne and whisk until combined. Place chicken in a shallow baking dish and pour over half the sauce. Cover with plastic wrap and set aside. Pour remaining sauce into a saucepan and simmer10 minutes. Combine cornstarch with 1 tablespoon water and stir into simmering teriyaki sauce. Continue to simmer until sauce is thick enough to coat the back of a wooden spoon. Remove from heat. Make the broccolini : In a large mixing bowl, combine olive oil, broccolini, and garlic. Place a large heavy-bottomed skillet over medium-high heat. Once skillet is hot, add broccolini and char until cooked through, 3 to 4 minutes per side. Set aside. Return skillet to stove and add 2 tablespoons olive oil. Drain chicken and pat dry, then add to skillet. Cook until chicken is golden and no longer pink, 6 to 8 minutes. Remove from heat and brush teriyaki sauce all over chicken pieces until thoroughly coated. Assemble bowls : Divide rice among 4 serving bowls and top with charred broccolini and spicy chicken teriyaki. Garnish with green onions, sesame seeds, and red pepper flakes, if using.