Finely chop the tomato and onion.
Heat olive oil in a pan and sauté the onion.
Add the tomato and cook together.
Place a tortilla on the pan.
Add the sautéed tomato and onion mixture onto the tortilla.
Sprinkle shredded cheese over it.
Cover with another tortilla.
Cook on low heat until both sides are golden brown.
Cut into bite-sized pieces to serve.