Texas Tater Tot Casserole

Name: Texas Tater Tot Casserole
Prep time: 30 min
Cook time: 40 min
Total time: 1 h 10 min
Cuisine: American
Ingredients: 3 tablespoons butter; 3 tablespoons all-purpose flour; 2 cups milk; 1/2 teaspoon fine sea salt; 1/4 teaspoon ground black pepper; 2 1/2 cups shredded cheddar or mixture of cheeses (divided (about 10 ounces total)); 10 ounces Ro-Tel style tomatoes ((tomatoes with chiles)); 2 cups chopped cooked brisket; 32 ounces frozen tater tots; 2 green onions (sliced); 2 tablespoons chopped cilantro; Sour cream (to serve)