chicken stock. simmer chicken in lightly salted water until tender about 10-15 minutes.cool chicken will be slightly undercooked.shred cooked chicken and then,just prior to serving,heat in 1 cup chicken stock.this will heat chicken without overcooking. in medium skillet,heat oil to 300 degrees.pass tortillas into hot oil for a few seconds to soften and seal.remove carefully and set aside between paper towels.do this just prior to assembly fill softened tortillas with shredded chicken and 1-2 tablespoons sauce.roll up and place seam-side-down in casserole.pour green sauce over top and garnish with sour cream and cheese. place in 375-degree oven 5-8 minutes or just long enough to melt cheese. note:sauce may be made a day in advance,but the dish is best when chicken is freshly prepared.