Line a baking sheet with foil and preheat the oven to 425 degrees. Rinse and dry the green beans then place them, the mushrooms, teriyaki sauce, and olive oil in a gallon sized plastic bag. Seal it up and toss the sauce with the vegetables until everything is well coated. Allow to marinate for about 10 minutes.

Spread the mixture out on a baking sheet, sprinkle evenly with salt and pepper, and roast for 20-25 minutes or until beans are crisp-tender and starting to look a little shrively and browned on the edges.

In a medium mixing bowl, use your fingers to gently mix together the ground chuck, garlic, teriyaki sauce, salt, and pepper. Gently pat into three burger patties, at least the size of your buns (they'll shrink when cooked).

Heat a cast iron skillet over medium high heat. Melt butter in the skillet, then add the patties. Cook for 4-5 minutes per side or until cooked to desired doneness (a little less for medium rare, a little more for well done). Towards the end of the cook time, place cheese slices on burgers and allow them to melt.

Remove the burgers from the grill and top with green beans, mushrooms, and french fried onions. Serve with a side of mayo mixed with a few teaspoons of teriyaki sauce.