Step 1

Bring 3 cups water to a boil in a large saucepan. Add polenta and miso and whisk vigorously to incorporate. Bring to a simmer and cook, whisking frequently in the beginning and less often as it thickens, until polenta is tender, 30–35 minutes. Season with salt. Keep warm over low heat until ready to serve.

Step 2

Meanwhile, cut dark green tops from spring onions and thinly slice; set aside for serving. Cut white and pale green parts into 3" pieces, halving lengthwise if thick; set aside. Heat 1 Tbsp. oil in a large nonstick skillet over medium-high. Cook tofu, tossing occasionally, until browned and crisp around the edges, about 5 minutes. Transfer to a plate.

Step 3

Heat remaining 1 Tbsp. oil in skillet and cook mushrooms, tossing occasionally, until browned, about 5 minutes. Add garlic and reserved white and pale green parts of spring onions and continue to cook, tossing often, until softened, about 3 minutes. Add asparagus and peas and cook, tossing occasionally, until bright green and beginning to soften, about 3 minutes. Add black bean sauce and ¾ cup water and bring to a simmer. Cook, stirring once or twice to incorporate sauce, until vegetables are crisp-tender and liquid is reduced by half, about 3 minutes.

Step 4

Transfer polenta to a platter. Top with tofu and vegetables. Spoon sauce over, then drizzle with chili oil. Finish with sesame seeds and reserved spring onion tops.