This Savory Mushroom & Onion Flatbread combines caramelized onions, earthy mushrooms, melted mozzarella and fontina, and Heat Street Detroit’s Green Michigan Tomatillo Verde Hot Sauce. Crispy, cheesy, and packed with flavor, this easy vegetarian flatbread is finished with bright tomatillo, lime, cilantro, and jalapeño for a fresh, tangy kick.