Heat a skillet with the oil. Add the onion and the salt; sauté for about 3 minutes until the onion begins to soften.
Add the grated carrot and the oregano (and another pinch of salt) and stir-fry together for another 1-2 minutes.
Meanwhile, warm the corn tortillas on a dry griddle or skillet until each side is lightly heated.
On two of the tortillas, sprinkle the grated cheese. Divide the carrot-onion filling between those two tortillas. Cover each with the remaining two tortillas (or fold if you prefer). Allow the cheese to melt and the tortillas to crisp a little.
Serve hot. I love topping mine with slices of avocado and a good salsa. This recipe works beautifully for breakfast, lunch or a quick dinner.