So simple, yet so yummy! These mushrooms really are different -- silky -- due to their very long simmer (passive) time. Serve warm on bread to absorb all the delicious liquid. My Nana made these mushrooms, and we would devour them on tangy Jewish rye bread for lunch - a much beloved family favorite. But, mostly we make them as appetizers or for parties - easy and you can make them ahead. Tip: food processor works fine for the onions and mushrooms.