Season one side of your Chuck Steak (2) with Salt and Pepper (to taste).
Preheat your oven to 400 degrees F (204 degrees C).
In a large pan add Olive Oil (1 1/2 tablespoon) and Unsalted Butter (1/2 tablespoon). Bring heat up to medium high.
Place your steaks seasoned side down on the pan. Cook for 3 minutes and then flip and then let them cook for another 3 minutes.
Dredge the Barbecue Sauce (to taste) over the steaks.
Using aluminum foil create a pouch and place the steaks inside, add the Onion (1/2).
Place your pouch with steak in the oven and cook for 45 minutes.
In a large pot with boiling water blanch the Green Beans (1 pound) for 2 minutes.
Turn off the heat and transfer the green beans into a bowl of ice water.
In another pan add some Unsalted Butter (1/2 tablespoon) and Olive Oil (1 1/2 tablespoon), add the White Mushroom (8 ounce). After sautéing for a bit add the other half of the Onion (1/2) and continue to cook for another minute.
Once the mushrooms and onions have cooked for a bit add the green beans back in. Cook for about 30 seconds over medium-high heat, stirring ofter. Season with Salt and Pepper (to taste).
Add the Garlic (1 1/2 tablespoon) and stir. Sauté for another 30 seconds.
Serve the green beans and mushrooms with the steak.