BLEND 1 cup broth, poblano chiles, 1 Tbsp. onions and 1 garlic clove in blender until smooth; transfer to saucepan. Blend 1/2 cup of the remaining broth, remaining onions, remaining garlic clove, tomato sauce, chipotle peppers and oregano in blender until smooth; pour into separate saucepan. Combine remaining chicken broth, sour cream and 1/2 cup cheese in separate saucepan.
COOK poblano and chipotle sauces on medium heat 5 min. or until heated through, stirring frequently; keep warm. Cook sour cream sauce 3 to 4 min. or until cheese is melted, stirring constantly.
TOP tortillas with chicken; roll up. Place, seam sides down, in 13x9-inch dish. Top with sauces, alternating colors to resemble the Mexican flag. Sprinkle with remaining cheese.