3lbflank steaktrimmed and cut into 1 1/2-inch cubes
Salt and pepper
12(8-inch) flour tortillaswarmed
1/2cupfresh cilantrocoarsely chopped
Adjust oven rack to lower-middle position and heat oven to 350 degrees. Arrange anchos and pasillas on rimmed baking sheet and bake until fragrant, about 5 minutes. Immediately transfer chiles to bowl and cover with hot tap water. Let stand until chiles are softened and pliable, about 5 minutes. Drain.
Process salsa verde, broth, orange juice, sugar, lime juice, oregano, salt, pepper, and drained chiles in blender until smooth, 1 to 2 minutes. Set aside.
Reduce oven temperature to 300 degrees. Pat beef dry with paper towels and sprinkle with 1/2 teaspoon salt and 1/2 teaspoon pepper. Heat 1 tablespoon oil in Dutch oven over medium-high heat until just smoking. Add half of beef and cook, stirring occasionally, until well browned on all sides, 6 to 9 minutes. (Adjust heat, if necessary, to keep bottom of pot from scorching.) Using slotted spoon, transfer beef to large bowl. Repeat with remaining 1 tablespoon oil and remaining beef.
Add onion and 1/2 teaspoon salt to now-empty pot. Reduce heat to medium and cook, stirring occasionally, until golden brown, 3 to 5 minutes, scraping up any browned bits. Add garlic and cumin and cook until fragrant, about 30 seconds. Stir in adobo, beef, and any accumulated juices until well incorporated and bring mixture to simmer.
Cover pot and transfer to oven. Cook until beef is tender and sauce has thickened, about 1 1/2 hours. Season with salt and pepper to taste. Serve with flour tortillas, sprinkled with queso fresco and cilantro.