In a 12-inch skillet over medium, heat the oil until shimmering. Add the turmeric and cook, stirring, until the oil takes on a yellow hue, about 15 seconds. Add the shallots and cook, stirring occasionally, until softened but not brown, 2 to 4 minutes. Add the garlic and cilantro stems, then cook, stirring, until fragrant, about 30 seconds. Add the mushrooms and ¼ teaspoon each salt and pepper. Cook, stirring often, until the mushrooms release some of their liquid, 3 to 5 minutes.