If you wash the mushrooms, they, especially oyster mushroom, tend to absorb water. You may choose not to wash the mushrooms. Regardless of whether I wash them or not, I spread them on a paper towel and let them stand for 1 hour or so at room temperature before cooking, so that the surface of the mushrooms is completely dry. This procedure also lets some excess moisture evaporate from the mushrooms themselves. I tear the trumpet royale lengthwise from the stem end. I just separate the oyster and clamshell mushrooms; if too large, I cut them into a bite size lengths.
In a large frying pan (I use a 12 inch non-stick, do not crowd the mushrooms) on a high flame and add peanut oil (1 tbs, I use peanut oil to begin and add butter later because of the high smoking point of peanut oil). When the oil is almost at the smoking point, I add the mushrooms. Any water left on the surface of the mushrooms will make the oil splatter. I do not salt at this time since it will draw out moisture from the mushrooms. I saute for several minutes or until the mushrooms develop brown spots on the surface. You should not see any liquid coming out at this point. I add pats of butter (less than 1 tbs) and turn down the heat to medium. When the butter melts, I add garlic (1 clove, finely chopped), salt and pepper and stir. At the end, I add soy sauce (2 tsp) from the side wall of the pan so that it will be heated and become fragrant before mixing into the mushrooms.
This is a simple and satisfying dish but to make it right, you have to make sure that liquid does not come out of the mushroom while cooking; drying the mushrooms before cooking and using high heat as described above are two of the secrets for success. We had this with cold sake but wines will be wonderful with this as well. Instead of soy sauce, you could use other herbs such as tarragon or thyme and also deglaze with Marsala, port, or sherry to make it more Western in style.