Cut the onion into thin wedges. Cut the broccoli stem into 1cm chunks, then cut the head into small florets. Thinly slice the spring onion. Thinly slice the garlic. Thinly slice the chilli, removing the seeds if less heat is desired. (The chilli is not essential to the dish; omit it if preferred.) Peel and finely grate half the ginger*.
Step 2 — Make sauce
Combine the garlic, chilli, ginger, rice wine vinegar, 1 tbs soy sauce, 2 tsp honey and 1 tbs water in a bowl.
Step 3 — Stir-fry beef
Separate the beef stir-fry and season with salt and pepper. Heat 1 tbs oil in a large deep frypan over high heat until very hot (fast and hot cooking is key to a great stir-fry). Stir-fry the beef for 1-2 mins until browned. Remove from the pan with a slotted spoon, leaving the flavoured oil in the pan.
Step 4 — Caramelise onion
Return the same pan to medium heat. Cook the onion, stirring occasionally, for 5-7 mins until tender and caramelised.
Step 5 — Char broccoli
While the onion is cooking, heat a medium frypan over high heat. Add the broccoli and 1 tbs water, cover and cook, stirring occasionally, for 4-5 mins until the broccoli is slightly charred and starting to soften. Remove from the heat.
Step 6 — Get ready to serve
Add the sauce to the onion, increase the heat to medium-high and stir-fry for 1-2 mins until slightly reduced. Add the beef and any resting juices and stir-fry for 30 secs or until warmed through. Divide the beef stir-fry and broccoli among bowls. Scatter over the sesame seeds and spring onion to serve.