In a bowl, mix together the dip ingredients. Set aside and keep cool.
Preheat the barbecue on medium-high (about 220 °C – 425 °F).
Using a knife, make shallow incisions in the skin of the duck breasts in a criss-cross pattern, taking care not to cut into the flesh. Season with salt and pepper.
Make thin slices in the potatoes, without cutting all the way through. Place the potatoes on an aluminum tray.
Cut each slice of bacon into four pieces.
Insert the bacon pieces and the dip into the incisions in the potatoes, alternating between each row. Season with salt and pepper.
Place the aluminum tray on the hot barbecue grill. Close the lid and cook for 30 to 35 minutes until tender. Remove from the barbecue and keep warm.
Increase the heat to high (245 °C – 475 °F). Turn off the burners on one side of the barbecue.
Place the duck breasts on the hot and oiled barbecue grill. Grill the breasts directly over the lit burners for 1 minute 30 seconds, starting with the skin side down and turning over once during cooking.
Transfer the breasts to the side of the grill with the burner off for indirect cooking, skin side down. Close the lid and cook for 8 to 10 minutes.
Return the breasts to the side with the lit burners, flesh side down on the grill. Cook for about 2 minutes or until the internal temperature of the breasts reaches 58 °C (137 °F) on a cooking thermometer. The duck breasts should be moderately firm to the touch and still pink inside.
Transfer the duck to a plate and cover with a sheet of aluminum foil. Let stand for 3 to 4 minutes before slicing or serving.
Meanwhile, melt the butter in a saucepan over medium heat. Add the herbs and garlic. Season with salt and pepper and simmer for 1-2 minutes.
Serve the sauce with the duck breasts and potatoes.