Spinach and Mushroom Enchiladas

Name: Spinach and Mushroom Enchiladas
Ingredients: 2 (10-ounce) cans tomatoes with chiles; 1 small onion, chopped; 1 garlic clove, minced; 2 teaspoons ground cumin; 2 tablespoons chopped cilantro leaves; 1 tablespoon chopped oregano leaves; Kosher salt; Freshly ground black pepper; 1 large red onion, diced; 1/2 pound portobello mushrooms, cleaned and cut into 1/2-inch pieces; 1 (10-ounce) box frozen chopped spinach, thawed and squeezed to remove excess water; 1/2 cup skim milk; 1 tablespoon cornstarch; 1 1/2 teaspoons ground cumin; 1 tablespoon minced chipotle in adobo (optional); 1 lime, juiced; 4 (6-inch) low-fat corn tortillas; 1/4 cup queso blanco