In a large heavy saucepan, heat the sesame oil over medium heat. Add the garlic, ginger root, and mushrooms and saute for 3 minutes, or until the mushrooms are just seared and still dry. Deglaze the pan with the vinegar and reduce over medium-high heat until almost no liquid remains. Stir in the sambal olek and salt and remove from the heat. Add the vinaigrette and tir to mix. Set aside and allow to marinate for at least 6 hours. The mushrooms can be kept covered in the refrigerator, for up to 4 days.