Very thin tortillas really make a difference with flautas.  Go to Lunas Tortilla Factory at McKinney and Woodall Rogers and request "tortillas muy delgaritas".  They will look at you strange since they all speak perfect English there.  After making your request, don't be surprised if they try to sell you something other than "tortillas MUY delgaritas".  The right thing is only sold in 20 dozen packages.  Heat vegetable oil in a small skillet (filled 1/4 inch deep) over high heat.  Quickly, submerge a tortilla in the hot oil (less than 5 seconds) and remove it to a dish.  Fill the tortilla with the beef or chicken filling.  Roll the tortilla and set aside as you process all the tortillas.  Use scissors to cut each flauta in half (easier to cook and eat).  Just before you plan to eat, return each tortilla to the hot oil and fry it on all sides until it is crisp.  Remove to a serving platter and serve with Cheese Dip and/or guacamole. 

Either Cheese Dip.  In a bowl, stir together all the ingredients.