Start by adding water, sriracha, soy sauce, garlic, sugar, and honey to a saucepan. Heat over medium until the mixture begins to bubble gently. Let it simmer for a minute so the flavors start blending together.
In a small bowl, whisk corn starch and cold water into a smooth slurry. Pour this mixture slowly into the simmering sauce. Keep stirring as it thickens, then reduce the heat to low.
Place the diced chicken in a bowl or plastic bag with the ⅓ cup of corn starch. Toss or shake until each piece is fully coated. This helps the chicken crisp up nicely during cooking.
Heat a skillet with a little oil over medium heat. Add the coated chicken and cook until golden brown on all sides. Make sure no pieces are left pink in the center and everything is cooked through.
Pour the thickened sauce over the cooked chicken. Stir until every piece is fully coated and glossy. Add red pepper flakes if you want more heat, then let everything simmer together for another minute.