Heat the vegetable oil in a large skillet or Dutch oven over medium heat. Add the chopped onion and sauté until it becomes translucent, about 5 minutes.
Add the minced garlic to the skillet and cook for an additional minute, stirring frequently.
Increase the heat slightly and add the chicken thighs to the skillet. Brown the chicken on all sides for about 5-7 minutes.
Sprinkle the sweet Hungarian paprika, ground cumin, salt, and black pepper over the chicken. Stir well to coat the chicken evenly with the spices.
Pour in the chicken broth, ensuring that the chicken is mostly submerged. Bring the mixture to a boil, then reduce the heat to low. Cover and simmer for 30 minutes until the chicken is cooked through and tender.
In a small bowl, mix the sour cream and flour until smooth. Gradually add some of the hot broth from the skillet to this mixture to temper it.
Slowly stir the tempered sour cream mixture back into the skillet, mixing well. Allow the sauce to simmer for an additional 5-10 minutes, stirring occasionally, until it thickens slightly.
Taste and adjust seasonings if necessary. Remove from heat and garnish with freshly chopped parsley before serving.