Arrange the taco shells in a baking tray, and bake them in the oven for 5 minutes at 350°F (180°C). After 5 minutes, remove the taco shells from the oven.
In a skillet, heat oil and saute the onion until it's soft and translucent. Add garlic, and cook it for a minute or until it's fragrant.
Add the shredded chicken, along with the seasoning and salsa. Cook for a few minutes then remove from heat.
In the arranged taco shells, add 1 tablespoon of refried beans, and about ½ cup of chicken salsa mixture. Top with shredded cheese.
Put back in the oven for a few minutes, until the cheese just melts. Remove from the oven, top with chopped chiles, shredded lettuce, avocado, sour cream, etc.