Preheat oven to 350 degrees F. See this site for a Red Enchilada Sauce recipe and make it at this time if you are making the sauce from scratch. After the sauce is prepared and ready, heat a large pan with oil over medium-high heat. Add onions and saute. Add diced chicken, Rotel and beans and cook this filling combination until hot.
Ladle some enchilada sauce on the bottom of a 9x13 pan. Assemble the enchiladas with a scoop of filling and a little enchilada sauce. Roll up and place enchilada fold-side down and line them up in the pan. Pour a good amount of enchilada sauce on top of the enchiladas and put the shredded cheese on top. Bake uncovered for 30 minutes or until bubbling. Garnish with cilantro and serve immediately. These can be easily frozen.