Peel and finely grate the ginger (see cooking tip). Shred the cabbage. Halve the cucumber widthwise, then thinly slice lengthwise. Stack the slices and cut into matchsticks. Shred the carrot using a julienne peeler or coarsely grate with a box grater. Pick the coriander sprigs, discarding the stems.
Step 2 — Make sauce and dressing
For the sauce, combine the ginger, hoisin sauce and 1 tbs water in a bowl. For the dressing, combine 1 tsp oil, 1 tsp soy sauce and ½ tsp white wine vinegar in a large bowl. Season lightly with salt and pepper.
Step 3 — Cook beef patties
Heat 1 tsp oil in a medium frypan over medium-high heat. Add the beef patties to the pan, season with salt and pepper, then cover and cook for 4 mins each side or until cooked through. Remove the patties from the pan, then drain the oil. Return the pan to high heat. Add the ginger hoisin sauce and cook, stirring, for 30 secs or until simmering. Remove the pan from the heat.
Step 4 — Coat patties
Cut each patty into 6 slices. Add the slices to the sauce in the pan. Cook over medium-high heat, turning, for 30 secs or until coated and hot. Remove the pan from the heat.
Step 5 — Toss slaw
Add the cabbage, cucumber, carrot, sesame seeds and fried shallots to the dressing and toss to combine.
Step 6 — Warm bao buns and serve
Remove the bao buns from the bag and put on a plate. Cover with a microwave-safe bowl and microwave for 2 mins or until fluffy and heated through. Spread the aioli over the inside of the buns, then fill with the wagyu strips and some of the slaw. Drizzle with the pan sauce and sriracha sauce, if using, then scatter with coriander. Serve with the remaining slaw.