Wash the Mushroom (1 pound) and pat dry with paper towel. Place mushroom slices in a large bowl or suitable jar.
Pour Vegetable Oil (2/3 cup), Distilled White Vinegar (1/3 cup), Salt (1 teaspoon) and Ground Black Pepper (1/4 teaspoon) into the bowl.
Add Dried Parsley (1 teaspoon), Dried Dill Weed (1 tablespoon), Onion (1), and Garlic (1 clove). Stir Well.
You can marinate in the fridge for at least 8 hours, or serve immediately if desired. If you keep it in the refrigerator, keep it covered.