Add chicken ingredients to a gallon-sized zippered bag. Smoosh around to combine and let marinate at least 4 hours (up to overnight).
In a small bowl, add onion, jalapeno, cilantro, salt and lime juice. Stir to thoroughly combine. Cover and place in refrigerator until ready to make the tacos.
In a saucepan over medium heat, add refried beans, milk and taco seasoning. Stir to combine. Once it starts to bubble, reduce heat to medium low and let simmer until ready to make tacos. Stir occasionally.
In a large saute pan over medium-high heat, add chicken - with all of the marinating liquid. Pan fry for 15 minutes, stirring regularly.
Heat up a grill pan over medium-high heat. Heat each tortilla for 30-45 second on each side, to desired darkness of grill marks. (spray with cooking oil if needed).
To build a taco, smear one half of tortilla with bean mixture and the other half with sour cream. Add portion of chicken to bean and then sprinkle with cheese and add a spoonful of onion mixture. Repeat with remaining tortillas.