Heat the oil on the stove in a small saucepan on medium-high heat. Line a baking dish with paper towels and set it near the stovetop.
While oil is heating, prepare guacamole by peeling the avocados, removing the pit, and mashing in a flat-bottomed container. Add lemon juice, ketchup, minced onion, chili powder, garlic powder, and hot sauce, if using. Mix together and chill.
Dice tomatoes and chop lettuce. Put in separate bowls and refrigerate.
Slice the cheese into 12 pieces. Place each piece inside a flout tortilla and fold sides in like an envelope. Fasten each cheese flauta with a wooden toothpick.
Turn oven on to heat at 200 degrees.
By now the oil should be hot. If the oil starts smoking, turn the heat down or remove the pan from the heat for a bit.
Using the metal tongs, dip each cheese flauta in the hot oil, one at a time. Hold in the oil for about 30 seconds, until the tortilla is browned. The cheese should be melted on the inside. After frying, place each flauta in the baking dish. After flautas are all fried, place the baking dish in the oven to keep the cheese flautas warm. Place the guacamole, tomatoes, lettuce, salsa, and sour cream (if using) on the table to serve with the flautas.