Sophisticated Kicked-Up Tater Tot Dish

SOPHISTICATED KICKED-UP TATER TOT DISH1 ¼ lb. beef top sirloinKosher salt/black pepper6 T. butter, divided1 c. yellow onion, diced1 c. red bell pepper, diced, plus extra for garnish1 c. poblano pepper, diced, plus extra for garnish8 oz. mushrooms, chopped¼ c.…