Preheat oven to 400 degrees.
Heat oil in a skillet over medium heat.
Add onions and cook 1-2 minutes while stirring.
Increase heat to medium-high and add turkey, stirring and cooking until browned (should reach a safe internal temperature of 165 degrees F). Drain excess liquid if needed (if you use leaner turkey, you may be able to skip this step).
Reduce heat to medium-low and add seasoning and beans. Stir to combine.
Add enchilada sauce and stir well. Remove skillet from heat.
Fill taco shells evenly with mixture. Place shells in a 9x13 pan and top with shredded cheese.
Bake uncovered for 5-7 minutes or until melted and heated through.
Serve immediately with toppings such as avocado, salsa, and sour cream.
