Oil your grids and preheat the grill to medium high, about 450°F.
Pat the chicken dry with paper towel and then rub it with the paprika and poultry seasoning. Then sear the chicken on the hot side of the grill so that colour forms on both sides, but the chicken is not cooked through. Turn the grill down to 350°F and set the chicken to the cool side of the grill while you make the sauce. Cook the chicken for about 20 minutes.
In a sauce pan melt the butter and caramelize the onion. When you are happy with the onion’s colour, add the garlic, sherry and sour cream. Season with additional paprika, salt, pepper and poultry seasoning.
Pour the sauce over the chicken in a grill safe baking dish and put on the “cool” side of the grill to bake for another 30 minutes or until the chicken is cooked through.
Serve with rice and vegetables.