Place the duck breasts on a chopping board and pat the skin dry with some kitchen paper. Using a sharp knife, score the skin lightly and sprinkle it with salt.
Put a medium-sized non-stick frying pan on the hob. Place the duck breasts in it, skin-side down, and slowly increase the heat. Fry gently, letting the fat melt out and the skin crisp up - this can take about 10 minutes but will depend on the size of your duck breasts and the heat of your pan.
Once the skin is gorgeously golden and crispy, turn over the duck breasts and cook for another 3-5 minutes. I like my duck quite pink so 3 minutes is enough for me.
Remove the duck breasts from the pan and set onto a plate to rest for 10 minutes. Pour the duck fat from the pan into a bowl and save for amazing roast potatoes.
Return the pan to the heat and add the hoisin sauce and honey. Stir well to combine, then bubble away for a couple of minutes until it thickens slightly - watch closely and moderate the heat so it doesn't burn. Turn off the heat.
Slice the rested duck breast, add to the pan with the hoisin-honey sauce and coat well.
To assemble: warm the bao buns in the microwave according to packet instructions. Spread some of the sauce from the pan onto each bao bun and top with some cucumber, spring onions, sliced radishes and a few slices of sticky duck. Sprinkle with sesame seeds and drizzle with a little sriracha mayo. Enjoy!