In a medium bowl, mix together the cornstarch, salt, black pepper, and Chinese five spice. Add the quartered chicken thighs to the bowl and toss to coat the chicken evenly with the flour mixture.

Heat vegetable oil in a large skillet or wok over high heat. Once the oil is hot, carefully add the coated chicken pieces in a single layer, making sure not to overcrowd the pan. Fry the chicken for 5-7 minutes, turning occasionally, until crispy and cooked through. You may need to fry the chicken in batches depending on the size of your pan.

Using a slotted spoon or tongs, remove the fried chicken from the pan and transfer them to a paper towel-lined plate to drain excess oil.

Discard all but 1 tablespoon of oil from the pan and return it to medium-high heat. Add the diced onion, red bell pepper, and serrano chili peppers to the pan. Stir-fry for 2-3 minutes, until the onion is slightly softened, stirring constantly.

Stir in the minced garlic and cook for another minute, until fragrant.

Return the cooked chicken to the pan and toss everything together, ensuring the chicken and vegetables are well combined. Cook over medium heat for a few more minutes to allow the flavors to meld together.

Garnish the Salt and Pepper Chicken with chopped fresh chives or scallions.