Add water, soy sauce, honey, sriracha, and garlic to a saucepan. Warm on medium heat until gently boiling.
Stir in the cornstarch slurry and simmer until the sauce becomes smooth, glossy, and slightly thickened.
Cut the chicken into even 1-inch pieces and toss with cornstarch until lightly coated.
Heat oil in a skillet over medium and cook the chicken in batches, 3–4 minutes per side, until golden and cooked to 165°F (74°C).
Pour the sauce over the cooked chicken and stir to coat. Cook for 1 more minute to blend flavors.
Garnish with sesame seeds and green onions. Serve over rice, noodles, or vegetables.