Combine all sauce ingredients in sauce pan over low heat until cheese melts; simmer over low heat an additional 20 mintues; set aside.
In skillet, brown beef and onion; add cheese; stir until melted; set aside.
Soften 2 packages of corn tortillas in hot oil; fill each tortilla with small amount of beef mixture and roll. Place in a 9x13 pyrex dish. Pour sauce over rolled enchiladas until covered. (you may have left over sauce}
Bake at 450 degrees for 10-15 minutes until hot and bubbly.