Trim the woody ends off the asparagus and slice thicker stalks in half lengthwise to ensure even cooking. Slice the mushrooms thinly and mince the garlic finely. Set all aside.
Heat the large skillet over medium-high heat, letting it warm up until it’s hot and slightly shimmering. Add the olive oil, swirling to coat the pan evenly.
Add the sliced mushrooms to the skillet. Sauté, stirring occasionally, until they release moisture and turn deep golden brown, about 5-7 minutes. You'll notice a smoky aroma as they brown and crisp edges form.
Push the mushrooms to one side of the skillet and add the minced garlic to the cleared space. Cook for about 30 seconds, stirring constantly, until fragrant but not burnt, filling the air with a savory aroma.
Lay the asparagus in a single layer in the empty side of the skillet. Cook for 3-4 minutes, turning occasionally, until the asparagus turns bright green and is just tender but still crisp. You’ll hear a gentle sizzle and see vibrant color.
Drizzle the soy sauce over the vegetables, tossing gently with tongs to coat everything evenly. Squeeze fresh lemon juice over the top, then toss again to distribute the bright, zesty flavor across the dish.
Sprinkle red pepper flakes if you like a bit of spice, and give everything one last gentle toss. Cook for another minute to let flavors meld and the glaze become slightly sticky.
Remove the skillet from heat and transfer the stir-fry to a serving plate. Let it sit for a minute to settle, then serve immediately while still hot, with the smoky aroma filling the room.