Preheat oven to 350°F.
Mix 1 cup of the sour cream, chicken, 1 cup of the cheese, 1/4 cup of the salsa, cilantro and cumin. Spoon about 1/4 cup of the chicken mixture onto each tortilla; roll up. Place, seam-side down, in 13 x 9-inch baking dish. Top with remaining 3/4 cup salsa; cover.
Bake at 350°F for approximately 30 minutes. Sprinkle with remaining 1 cup cheese; continue baking until cheese is melted. Top with lettuce and tomato. Serve with remaining 1 cup sour cream.