What is the secret orange meat marinade recipe in Hispanic markets. (ie chicken fajitas etc)

Achiote paste gives it the color and to some extent the coating. To that you add orange and lime or sour oranges if you can get them, then onions and garlic and Mexican oregano. You can make your own paste from annato but that is a labor of love.

Sunny D use to work at one.

Orange juice, Adobo powder, garlic, Lime (cut in half). And a packet of 'sazon' seasoning.

Here is my version if you're interested:

http://food52.com/recipes/7207_flank_steak_in_mojo_criollo

Orange juice olive oil and garlic Not sure of the proportions

You may be thinking of mojo (pronounced MOE HOE). I like Bobby Flay's recipe for homemade, but you can also buy it in bottles from Mexican grocers. Rick Bayless also has a great lime and garlic mojo recipe.

Is it adobo? See http://www.goya.com/english/product_subcategory/Condiments/Adobo