Juice half the lime*, then cut the remaining lime into wedges. Thinly slice the cabbage with a sharp knife or mandoline. Slice the apple lengthwise. Stack the slices and cut into matchsticks. Thinly slice the spring onion on an angle.
Step 2 — Cook rice
Rinse the rice until the water runs clear. Put in a small saucepan with 250ml (1 cup) water, cover and bring to a simmer over medium heat. Reduce the heat to low and cook for 12 mins or until tender and the water is absorbed. Turn off the heat and stand, covered, for at least 5 mins.
Step 3 — Crumb salmon
Meanwhile, whisk 1 egg in a bowl. Combine 1 tbs flour and a pinch of salt in a shallow dish. Put the breadcrumbs in a separate shallow dish. Pat the salmon dry with paper towel. Dust the salmon with the flour, shake off the excess, then dip in the egg and coat in the breadcrumbs.
Step 4 — Fry salmon katsu
Heat 1cm oil in a small frypan over medium heat. Cook the salmon for 4 mins each side or until golden and cooked through. Drain on a wire rack set over paper towel (this will keep the crumb crisp). Season with salt.
Step 5 — Prep salad and sauce
While the salmon is cooking, put 2 tsp lime juice and 1 tsp sugar in a large bowl, season with salt and pepper and stir until the sugar dissolves. Add the cabbage and apple and toss to combine. Set aside. Heat the tonkatsu sauce in a small saucepan over medium heat, stirring occasionally, for 2-3 mins until warm.
Step 6 — Get ready to serve
Add the sesame oil and half the sesame seeds to the rice and fluff with a fork to combine. Divide the rice, apple and cabbage salad and salmon among bowls and drizzle the katsu sauce over the salmon. Scatter with the spring onion and remaining sesame seeds. Serve with the lime wedges and wasabi, if desired.