season the meat
Combine rosemary, coriander, sugar, salt, and pepper in a bowl. Half an hour before grilling, take the meat from the fridge. Place the chicken breast-side down with the wings facing towards you on a working surface. Use a sharp knife or poultry shears to cut down the side of the backbone to split the chicken in half. Turn the chicken and flatten the chicken with your hands by pressing on the breast. Place on a baking sheet and season with the spice mix on both sides. Set aside until needed.
prepare the grill
Heat your gas grill or fire up the grill to get the grill temperature to about 250 °C or 480 °F. When the grill is hot, clean the rack with a long brush and lightly grease it with oil (the easiest way to do this is by dipping a paper towel into the oil). Place the chicken in the indirect fire spot on the grill. Grill for 30 minutes, turning once after 15 minutes. Then transfer the chicken to the hottest area of the grill and cook the meat for 5 minutes on each side or until golden-brown and slightly charred.
When the chicken is done, transfer it to a plate, set aside for 10 minutes, and cut it into serving portions. Make the homemade sauce. In a bowl, combine chopped parsley, minced garlic, vinegar, apricot jam, and olive oil. Season to taste with salt and pepper, and pour over the grilled chicken.