Remove the skin from the duck fillet and cut off the fat – we won't need it. Season the fillets with a little salt and pepper.
Prepare the marinade by mixing sesame oil, soy sauce and honey. Marinate the fillets for 30 minutes.
Then preheat the grill. Dry the fillets. Place under the grill for 4-5 minutes, turning over if the grill is not in contact. Wrap the duck in foil, keeping it warm.
In a small saucepan, mix the orange juice with starch, add the whole marinade and cook until thickened. Remove from the heat.
Cut the fillet into slightly larger pieces than the grapes you will have. Brush them with thick marinade on all sides.
Put the pieces on skewers alternately with grapes.