Another meal of Leftovers--Masher Bites!

This meal was inspired by the Masher Bites at The Best Little Roadhouse. And also by the leftover steak and mashed potatoes in my fridge!
The menu describes the Masher Bites as, "Tenderloin and button mushrooms sautéed in red wine demi-glace served over our garlic mashed potatoes."
So--that was my goal! (Even though I don't know what a "demi-glace" is!)
I didn't measure much of anything in this--so I apologize. But, I can give you the gist of it.
First, I melted butter and mixed in some flour. Then, I added beef broth and marsala wine, garlic, and a little worcestershire sauce. I let it simmer and thicken.
While that simmered, I sauteed mushrooms, onion and garlic in a little butter. I added that to the sauce.

Then, I sliced the steak very thinly and warmed it in the same pan I cooked the onions and mushrooms in. Slicing it very thinly allows the steak to heat up, without overcooking it.

I had some mashed potatoes (and cauliflower!) leftover, and I just added another potato or two to the mix and mashed them in. (I didn't do garlic mashed potatoes--no time!)
Anyway, I served the steak and sauce with the mashed potatoes and a salad and it was great!
Ryan, in typical three year old fashion, at first absolutely refused to eat anything. We made him take a few bites and then he decided that he liked it after all!
It was really good, and a great way to use leftovers that would have gone to waste otherwise!