Mix together the colby jack cheese and the chopped onion, reserving about 1/2 cup of the colby jack cheese for sprinkling over the top, at the end.

Quickly cook tortillas in hot oil only enough to softened them. (Cook them too long, and your gonna have to make tostadas.) Drain well on paper towels. Set aside.

Preheat oven to 350 degrees F.

Pour 1/4 cup of the enchilada sauce into the bottom of a 9x13'' pan.

Fill each corn tortilla with a handful of cheese/onion mixture. Roll tightly, and place seam side down in the pan.

Pour remaining enchilada sauce over the top. Top with remaining 1/2 cup of cheese.

Bake for 20-25 minutes or until hot and bubbly. Remove from oven and let cool 5 minutes.

Top with shredded lettuce, cotija cheese, tomatoes, cilantro, and sour cream.