Heat 1 tablespoon olive oil in a large skillet over medium heat until shimmering.
Add the cubed chicken and cook, stirring occasionally, until browned on all sides, about 5–7 minutes; remove with a slotted spoon and set aside.
Add the diced onion, sliced celery, diced green pepper, and minced garlic to the skillet and cook over medium heat until the vegetables begin to soften, about 5 minutes.
Return the browned chicken to the skillet, then sprinkle in the paprika, crushed red pepper flakes (if using), cayenne, and dried oregano; stir to coat the chicken and vegetables with the spices.
Add the 28 ounces petite diced tomatoes and the bay leaves, stir to combine, and bring to a gentle simmer.
Simmer uncovered over medium-low heat for about 10–15 minutes, until the chicken is cooked through and the flavors meld; remove and discard bay leaves before serving.
