Bring a medium pot of water to a rolling boil while you prep. Use plenty of water so the soba can move freely; this prevents clumping and ensures even cooking.

Prep the aromatics and components: slice the shiitake, cube the silken tofu gently and set on a plate, separate scallion whites and greens and thinly slice, chop cilantro, zest the lemon, and measure sesame seeds and chili crisp. Having everything ready lets the broth come together quickly and keeps the tofu intact when it’s added.

Cook the soba: add the 160 g soba to the boiling water and cook according to package directions (typically 4–5 minutes). Stir gently once or twice to keep noodles separate. Cook until al dente — you want a little bite so they don't go mushy when reheated in the broth.

Drain the noodles in a colander and rinse briefly under cold running water to stop the cooking and remove surface starch. Rinsing keeps the broth clearer and prevents the noodles from continuing to soften in the hot broth. Set aside in the colander to drain well.

In a medium sauté pan or small skillet, warm 1 tsp of the toasted sesame oil over medium-high heat until shimmering. Add the sliced shiitake and the white part of the scallions; cook undisturbed for 1–2 minutes to encourage browning, then toss and continue until edges are golden (about 3–5 minutes total). Browning the mushrooms builds Maillard-sweet, smoky notes that give the broth a deeper, 'smoky' profile without adding smoked ingredients.

Meanwhile, heat the 600 ml hot vegetable stock in a separate small saucepan until steaming but not rolling. Remove roughly 2–3 tablespoons of the hot stock into a small bowl and whisk in the 2 tbsp white miso until smooth to make a miso slurry. Do this because miso dissolves unevenly and should not be boiled directly; the slurry lets you blend it smoothly into the stock off the heat.

Add the sautéed shiitake (and any browned bits) into the hot stock, reduce heat to low, and stir in the miso slurry off the boil. Keep the stock at a gentle warm (not boiling) — boiling miso can dull its bright umami and ruin the delicate enzymes and flavors. Taste and season with 2 tsp light soy sauce and a pinch of sea salt if needed (remember miso and soy are already salty).

Warm the tofu and greens: add the baby kale or winter spinach and the cubed silken tofu to the warm miso-shiitake broth and let them gently heat for 1–2 minutes, using a gentle spoon to move the tofu without breaking it apart. Silken tofu is fragile; short, gentle warming lets it absorb flavor without turning to mush.

Finish the broth: stir in the remaining 1 tsp toasted sesame oil and the lemon zest off the heat to preserve aroma and brightness. If you want an extra smoky note, add 1/2–1 tsp chili crisp while still warm (optional). Keep the broth warm but do not boil.

Reheat the noodles briefly: place the drained soba back into the (now-empty) hot pot for 20–30 seconds or pour a ladle of hot broth over them — this gently brings them back up to temperature without overcooking, and allows them to pick up some broth flavor.

Assemble bowls: divide the reheated soba between two bowls. Ladle the miso-shiitake broth with tofu and greens over the noodles. Arrange the browned shiitake attractively on top, then scatter scallion greens, chopped cilantro, toasted sesame seeds, and a light grating of lemon zest. Drizzle additional chili crisp on one side of the bowl for those who want heat.

Final seasoning: finish with freshly cracked black pepper and a quick taste — adjust with a small splash of soy or a pinch of salt if needed. Serve immediately so the tofu stays silky and the greens stay bright.