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 tight 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. Toss with sesame seeds before serving, if desired.