Preheat the oven to the warm setting or about 200 degrees F.
Fill a large saucepan with about ¾ inch oil. Heat over medium heat to 375 degrees F. You only need enough oil to come about halfway up the flautas, which makes them easier to turn and keeps the frying process simple.
In a medium bowl, combine shredded beef, cheese, salsa, diced chiles, garlic salt, and pepper.
Working with one tortilla at a time, spoon about ¼ cup filling in a line down the center of each tortilla. Spoon the filling in a narrow line across the tortilla, then roll tightly around the filling and secure with a toothpick.
Using tongs, hold each flauta in hot oil until firm, then release to continue cooking. Cook until golden brown or about 2 minutes. Hold each flauta over the pan for a few seconds and tilt it slightly to let any oil drain from the inside before placing it on paper towels.
Transfer flautas to an alumiunium foil-lined baking sheet and keep warm in the oven while assembling and cooking the remaining tortillas. Serve warm with toppings.