Sesame-Crusted Tuna with Asian Greens

Ingredients

• 4 tuna steaks, about 180g each
• 1 tbsp toasted sesame oil
• 3 tbsp black sesame seeds
• 3 tbsp white sesame seeds
• 1 tbsp neutral oil, such as sunflower
• 2 tbsp rice wine vinegar
• 20g fresh ginger, finely grated
• 2 garlic cloves, finely grated
• 3 tbsp soy sauce
• 1 tsp honey
• 1 tbsp toasted sesame oil
• 1 lime, juiced
• 250g tenderstem broccoli, trimmed
• 2 garlic cloves, thinly sliced
• 4 pak choi, halved lengthways
• 1 tbsp neutral oil
• 300g cooked soba noodles, drained and tossed in a little sesame oil, to serve
• 4 spring onions, finely sliced on the diagonal, to serve
• 1 fresh red chilli, finely sliced, to serve

Method

1. Mix the black and white sesame seeds together on a flat plate and season generously with salt and pepper — this is your only chance to season the crust itself. Pat the tuna steaks dry on both sides (water means steam, and steam means no crust), brush each one with the toasted sesame oil, then press firmly into the seeds on all sides until thoroughly coated.
2. Whisk together the soy, rice wine vinegar, sesame oil, grated ginger, grated garlic, honey and lime juice in a small bowl until the honey dissolves. Taste — it should be sharp, salty and savoury all at once. Most of the salt comes from the soy, but a final pinch of seasoning ties it together.
3. Cook the soba noodles according to the packet instructions in well-salted water, drain, rinse under cold water and toss with a little sesame oil to stop them sticking. Set aside.
4. Heat the neutral oil in a large wok or heavy frying pan over a high heat until just smoking. Add the tenderstem broccoli in a single layer and stir-fry for about 3 minutes, until the stems are bright green and beginning to char at the edges. Don't crowd the pan — if the broccoli won't fit in one layer, do it in two batches, or it'll steam grey instead of charring.
5. Add the pak choi cut-side down along with the sliced garlic and stir-fry for a further 2–3 minutes, until the pak choi is wilted and golden where it met the pan. Keep it moving — the garlic wants 30 seconds to turn fragrant and pale gold, no more. Burnt garlic turns the whole dish bitter. Pour over half the dressing, toss to coat and slide off the heat.
6. Wipe the pan clean and return it to a high heat. Add the neutral oil and heat until shimmering — you want it just short of smoking so the sesame seeds toast on contact rather than scorching.
7. Lay the tuna steaks in the pan with space between them — searing four at once will crowd the pan and drop the heat. Work in two batches if needed. Sear for 90 seconds per side, until the sesame crust is deeply golden and the fish is still rare and ruby at the centre. Lift onto a board and rest for 1 minute — the residual heat carries the edges to medium-rare while the middle stays cool.
8. Taste the dressing one more time, adjust now — at the end, not at the table — then slice each tuna steak thickly against the grain.
9. Divide the soba noodles between four bowls, pile the charred greens alongside and lay the sliced tuna over the top. Spoon the remaining dressing over everything, scatter with the spring onions and red chilli, and serve with lime wedges for squeezing at the table.