Mexican Marinated Mushrooms And Onions - cooking recipe

Ingredients

12 ounces fresh button mushrooms, cleaned and stemmed
1/3 cup olive oil
1/3 cup balsamic vinegar
3 cloves minced garlic
1 teaspoon crushed red pepper flakes (or to taste)
1/4 teaspoon Mexican oregano (we use plain oregano)
salt and pepper
1 large Spanish onion, sliced into rings

Preparation

Place the mushrooms in a flat serving dish.
Place the rest of the ingredients into a small heavy saucepan.
Bring the ingredients to a boil and cook until the onions soften.
Pour the marinade over the mushrooms and arrange the onion slices around the mushrooms attractively.
Let the mushrooms marinate at room temperature for 4 hours, stirring frequently.
Refrigerate for at least 24 hours.