Heat bacon grease in a large skillet over medium heat. Add onion, garlic, salt, red pepper flakes and paprika. Stir together and saute until onion is translucent. Add chicken pieces and pour water over all. Cook over medium heat for 1 hour, adding more water if necessary.
Stir in tomatoes, reserving liquid. Stir liquid into a medium bowl with flour and sour cream; mix until well blended, then slowly add mixture to chicken, stirring constantly. Cook until mixture is thick.