Heat the olive oil in a large skillet over medium-high heat until shimmering. Add the mushrooms and garlic and sauté for 2 to 3 minutes, stirring frequently, until the garlic is fragrant and the mushrooms start to brown.

Reduce the heat to medium, sprinkle with a pinch of salt, and stir. Cover the skillet and cook for 5 to 7 minutes, stirring occasionally, until the mushrooms have softened and released their juices.

Remove the lid and if there is too much liquid, cook uncovered for 1 to 2 minutes over medium heat until it evaporates. Stir in the soy sauce and toasted sesame oil.

Take the skillet off the heat, add half of the sliced green onions, and toss to combine. Season with salt and pepper to taste. Serve topped with the remaining green onions.