1) Heat griddle to medium-high.
2) Score the skin-side of the duck with a knife in a lattice pattern, being sure not to cut through to the flesh. Season each breast with salt and pepper on both sides.
3) Rub the skin side of each breast with a few tbsp of the rub and place on the griddle, rub side down, and griddle until slightly charred and the skin begins to get crispy, about 4 to 5 mins.
4) Turn the breasts over, brush with some of the glaze and continue barbecue to medium-rare doneness, another 3 to 4 mins.
5) Remove the duck from the griddle and brush with more of the glaze. Let rest for 5 mins then slice 1/2cm thick on the diagonal. Place the griddled spring onions on a platter and top with the sliced duck breast. Serve with warm tortillas.
For the Asian spice rub:
1) Combine all ingredients in a small bowl.
For the ginger-garlic-chilli glaze:
1) Heat oil in a small saucepan over medium heat.
2) Add ginger and garlic and cook until soft.
3) Add the chilli paste and cook for 1 mins.
4) Whisk in the honey and soy and cook until just combined and the honey has melted. Let cool before using.