Carefully pull oyster mushrooms apart into pieces, keeping smaller mushrooms clustered and cutting larger mushrooms in half so that they are all roughly the same size.

Heat olive oil in a large skillet over medium-high heat until shimmering. Add the mushrooms and stir to coat them in oil. Let the mushrooms cook, stirring only occasionally to encourage browning, until reduced in volume and browned, 7 to 8 minutes.

Finely chop the shallot and the leaves from tender herbs until you have 1 tablespoon of each.

Add the shallots, unsalted butter, kosher salt, and black pepper to the pan. Cook, stirring occasionally, until the shallot is softened and the mushrooms are well browned, 2 to 3 minutes.

Sprinkle with the herbs and flaky salt if desired.