Preheat oven to 450°.

Trim ends off of green beans. In bowl, add the green beans, toss with a little salt & pepper, add the balsamic vinegar, toss well. Place beans on a baking sheet and bake for 20 minutes.

In a frying pan, over medium heat, cook steaks - seasoning with salt & pepper as you place them in the pan.

In a sauté pan, over medium heat, add olive oil, onion & garlic, cook. When onion starts to soften, add mushrooms. Cook mushrooms for 15 minutes.

While mushrooms are cooking, make the 1 C. of beef broth (microwave water and cube in a measuring glass on high for 1-2 mins and stir) and the cornstarch slurry (mix water and starch together).

After the mushrooms have cooked the 15 minutes, add the broth, cornstarch slurry, butter and lemon juice. Mix well and simmer.

Sauce will begin to thicken. Once sauce is thickened to your desired consistency, stir in the parsley.

Serve mushroom sauce over the steaks, and green beans on the side.