Bring a large pot of salted water to a full rolling boil. Add the 400g of dried wheat noodles and cook according to the package directions until just al dente — typically 4–5 minutes for lo mein style, slightly longer for udon. The noodles should be cooked through with just a faint resistance when bitten — they will not receive any further cooking in the wok beyond reheating during tossing, so the texture at draining is essentially the texture at serving. Before draining, reserve 120ml of the starchy noodle cooking water in a heatproof jug. Drain the noodles and rinse briefly under cold running water — the cold rinse stops the cooking immediately, preventing the noodles from continuing to soften through residual heat, and removes the excess surface starch that would cause the noodles to clump together during the wait before wok cooking. Immediately toss the rinsed, drained noodles with the 15ml of toasted sesame oil, tossing to coat every strand. The sesame oil provides flavour and prevents sticking — without it, noodles left to rest will bond into a solid mass. Set aside.

Before making the chili oil or heating the wok, prepare the sauce base — this ensures it is ready to pour immediately during the wok cooking step without any delay. In a small bowl, combine the 60ml of soy sauce, 45ml of Chinese black vinegar, 30ml of toasted sesame oil, 25g of sugar, and 8g of MSG. Whisk until the sugar has completely dissolved and the mixture is uniform. The sauce base is the flavour framework of the entire dish — the soy provides salt and deep savory umami; the Chinese black vinegar provides a specifically complex, slightly malty, moderately acidic note that regular rice vinegar or balsamic cannot replicate; the sesame oil provides nutty, toasted aromatic richness; the sugar balances the soy's saltiness and the vinegar's acidity; the MSG amplifies every other flavour compound present simultaneously. The substitution of salt for MSG is noted in the ingredients — salt provides saltiness without the additional glutamate that enhances the perception of all other flavours, so the result without MSG will be good but less vivid. Set aside.

This step requires precise oil temperature management — it is the technique decision that determines whether the chili oil smells of toasted, aromatic spice or of burnt bitterness. Heat the 120ml of vegetable oil in a small saucepan over medium heat. Monitor the temperature — the target is 175–180°C. If you do not have a thermometer, test by inserting a wooden chopstick vertically into the oil: at the correct temperature it should produce a steady, vigorous stream of small bubbles rising from the tip. Remove the saucepan from the heat when the temperature is reached, and allow to rest for 2 minutes — this brief rest drops the temperature slightly, providing a margin of safety against burning the spices on contact. Place the 40g of gochugaru and 15g of lightly crushed Sichuan peppercorns in a heatproof bowl. Add the 45g of minced garlic and 30g of minced ginger on top. Carefully pour the hot oil in a slow, steady stream over all the spices and aromatics. The mixture will sizzle vigorously and steam significantly — this is correct and expected. The hot oil flash-extracts the fat-soluble aromatic compounds, capsaicin, and colour pigments from the gochugaru and peppercorns simultaneously, and blooms the garlic and ginger's aromatic compounds into the surrounding oil. At the correct temperature, the gochugaru turns the oil a vivid, deep red-orange and the mixture smells of toasted spice, garlic, and warmth. If the oil is too hot, the gochugaru will darken to brown immediately and the mixture will smell of burnt chili rather than toasted — discard and start again. Stir the chili oil and allow to steep for at least 5 minutes while the remaining preparation continues. The longer it steeps, the deeper the flavour extraction.

Heat a large wok or deep skillet over high heat until genuinely smoking hot — this requires 2–3 minutes of preheating over the highest available flame. Wok cooking's specific results depend on the extremely high temperature that produces the slightly charred, smoky flavour known as wok hei — the particular aroma and taste of high-heat wok cooking that cannot be produced at the lower temperatures of a moderately hot pan. Add 30ml of the prepared chili oil to the smoking wok — use a combination of the infused oil and some of the solid spice mixture, or strain for a cleaner visual presentation while still using the deeply flavoured oil. The moment the oil hits the smoking wok, add the white scallion parts, the 45g of minced garlic, and the 30g of minced ginger simultaneously. Stir-fry for 45 seconds — moving continuously with a wok spatula or tongs, turning the ingredients against the hot wok surface rather than simply stirring. At this temperature the garlic and ginger's aromatics bloom explosively — the result should smell intensely fragrant within 20 seconds of hitting the wok. Add the 150g of thinly sliced shiitake mushrooms. Stir-fry for 2–3 minutes, keeping the vegetables moving but allowing brief moments of stationary contact with the hot surface — these brief contacts produce the slight caramelisation at the mushroom edges that adds smoky depth. The mushrooms will release moisture initially, which the high heat evaporates almost immediately, then begin to caramelise. Add the 200g of halved bok choy. Stir-fry for 1–2 minutes until the leaves wilt and the stems turn bright green with slight char marks at the cut edges. Season with the 6g of kosher salt.

While the vegetables cook, or immediately after, fry the eggs in a separate non-stick skillet. Heat the 15ml of vegetable oil in the skillet over medium-high heat until shimmering. Crack all 4 eggs into the pan, keeping them separate. Fry for 2–3 minutes without disturbing — the edges should develop a crispy, lace-like golden-brown border while the yolk remains completely liquid. This is the classic Chinese-style fried egg — crispy at the edges and bottom, runny at the top — that provides the textural contrast between its crisp exterior and liquid yolk against the noodles. Remove from heat when the whites are fully set but the yolk moves freely when the pan is gently shaken.

Add the sesame-tossed noodles to the wok with the stir-fried vegetables. Pour the entire sauce base over the noodles. Add 60ml of the reserved noodle cooking water. Toss everything together vigorously for 1–2 minutes using tongs or chopsticks — lifting from the bottom and folding over the top, working quickly to coat every strand of noodle in the sauce and distribute the vegetables evenly throughout. The noodle cooking water's starch emulsifies the oil-based and vinegar-based components of the sauce into a cohesive, slightly thickened coating rather than the oily, separated liquid that would result without it. Add more noodle water in 15ml increments if needed — the noodles should be glossy and uniformly coated, not dry or swimming in excess liquid.

Add the green scallion parts and half of the 100g of cilantro to the wok. Toss for 30 seconds — enough to briefly wilt the green scallions and distribute the cilantro without fully cooking either. Remove from heat immediately. Divide among four serving bowls. Place one fried egg over each bowl. Scatter the remaining cilantro over each bowl. Scatter the 20g of toasted sesame seeds across all four portions. Drizzle additional chili oil from the batch — as much or as little as the heat preference of each person at the table dictates — over each bowl. Serve immediately.