Found one of the pollo asada recipes...
Marinade:
· 1 cup fresh orange juice
· 1 cup fresh lime juice
· 1/2 cup fresh lemon juice
· 1/4 cup ancho chile powder
· 2 tablespoons paprika
· 4 cloves garlic, coarsely chopped
· 1 cup olive oil
It says to marinate it for an hour... feel free to go longer than that.
The absolute most important thing is to use FRESH SQUEEZED juice. If you buy lemon and lime juice in a bottle you deserve your own fate.