In a large skillet or pot, heat the vegetable oil over medium heat.
Add the chicken pieces and cook until browned and cooked through. Remove the chicken and set aside.
In the same skillet, add the chopped onion and minced garlic. Sauté until the onion is soft and translucent, about 5 minutes.
Stir in the chopped bell pepper and tomatoes. Cook for another 5 minutes until the tomatoes begin to break down.
Pour in the chicken broth and bring to a simmer.
Stir in the ground cumin, dried oregano, paprika, and cayenne pepper (if using). Cook for 2-3 minutes to combine the flavors.
Reduce the heat to low and stir in the heavy cream and sour cream. Cook gently until the sauce is creamy and well combined.
Return the cooked chicken to the skillet. Simmer for 5-10 minutes to heat through and allow the flavors to meld. Adjust seasoning with salt and black pepper to taste.
Garnish with chopped fresh cilantro before serving.
Enjoy your meal!