First if using rotisserie chicken, shred and chop the chicken. If you have raw chicken, cook and make shredded chicken but be sure to chop it into pieces. Preheat the oven and pre-bake the taco shells according to the package.
In a pot on medium high heat with a little oil add in the diced onion and the can of Rotel tomatoes. Cook until the onions become translucent then toss in the beans and chicken.
Now, add in both taco seasoning packs then water. Allow the pot to come to a boil then lower to a simmer for 10 minutes. This allows time for the seasoning packet to do its job.
Now, the taco shells should be finished. Place them standing up in a baking dish. The baking dish is a lot more secure than a sheet pan without sides. Stuff the shells with the filling then top with cheese.
Place in preheated oven for about 10 minutes or until you've noticed the cheese has melted.
Finish the baked chicken tacos with chopped cilantro and a squeeze of lime.