Heat olive oil or butter in a large skillet or Dutch oven over medium heat.
Add chopped onions and garlic, sauté until golden and fragrant.
Season chicken pieces with salt and pepper, then add them to the pan. Brown on all sides for 5–7 minutes.
Sprinkle in paprika (sweet and hot, if using) and stir to coat the chicken evenly.
Pour in chicken broth and diced tomatoes (if using). Bring to a simmer.
Cover and let the chicken cook gently for 25–30 minutes, until tender and cooked through.
In a small bowl, mix sour cream with a few spoonfuls of hot sauce from the pan (to temper).
Reduce heat to low, then stir in the sour cream mixture to create a creamy, rich sauce. Do not boil after adding.
Taste and adjust seasoning. Garnish with fresh parsley.
Serve hot over egg noodles, rice, or Mashed Potatoes