Heat the oil in a large non-stick skillet. Add the eggs and cook and scramble them until just cooked through. Make a row of the eggs along the centre of each tortilla. Arrange the cheese, salsa and lettuce alongside the egg. Fold over the sides of the tortilla and then tightly roll into a closed cylinder. Slice in half at a slight angle, if desired. Serve additional salsa and sour cream, if desired.