Preheat oven to 400F Heat oil in skillet over medium heat and saute onion and garlic until softened, stirring occasionally about 10 minutes. Stir in cumin and oregano.
Remove from heat and stir in lime juice. Place 2 tortillas on a baking sheet and spread the onion mixture equally on the two. Sprinkle with equal amounts of cheese. Top with remaining tortillas and bake at 400 F for about 8 minutes until the edges are golden. Let stand 5 minutes and cut each into sixths with a pizza
cutter. Garnish with salsa, guacamole and sour cream if desired.