For steak tacos I have the steak run through a machine so it is flat. I haven't tried pounding the chicken flat when making this but I think it may work better. Consider this an optional step, as every time I've made it without pounding it, it still comes out fantastic but it takes a while to cook. Maybe split breasts would be good.
Season meat by sprinkling with Adobo, Cumin, and Pico de Gallo seasoning. I like to use the adobo that has cumin in it and if you choose to go this route, you don't need to use any extra cumin. If you like spicy food use more pico seasoning, if you like mild use a smaller amount.
Rub seasoning into meat thoroughly.
Layer meat, onions, and garlic in a deep pan or bowl. I have also begun layering lime slices along with it.
Pour mango nectar and lime juice over meat so that the liquid just covers the top of the meat. I use about a 3 part mango nectar, 1 part lime juice mix.
Let sit for several hours or over night.
Cook on hot grill.
Serve with warm tortillas and desired taco toppings.
An alternate cooking method:.
I had the guy at the meat counter cut up the chicken into taco meat, if you shop at a hispanic grocery store they'll know exactly what you mean if you ask them to cut it for tacos but basically its just cutting it into small chunks. I still marinaded everything the same way, rubbing the seasonings into the meat is more difficult but still doable. Instead of grilling the meat however, after everything marinaded I put the whole mixture, marinade and all in a slow cooker. I wouldn't use lime slices in the marinade for this though so you won't have to pick them out.