How to Make It
Preheat oven to 400°F. Heat oil in a large skillet over medium. Add cumin and cook, stirring often, until fragrant, about 30 seconds. Add onion, poblano, and ½ teaspoon salt and cook, stirring occasionally, until softened, about 10 minutes. Add corn and cook, stirring, until tender, about 2 minutes. Remove from heat and stir in beans and 1 cup cheese. Set aside.
Process tomatillo salsa, green chiles, cilantro, ¼ cup sour cream, and remaining ½ teaspoon salt in a blender until smooth.
Spread ¾ cup sauce in the bottom of a 2-quart baking dish. Place about ½ cup bean mixture in each tortilla, roll up, and lay seam side down in dish. Top with remaining sauce and cheese. Bake until bubbling and beginning to brown, about 20 minutes. Let stand for 10 minutes. Top with remaining sour cream and cilantro.