1) The gas or charcoal grill must be prepared for medium to high direct heat.
2) Orange zest, garlic, salt, sugar, cumin, oregano and chili powder must be stirred together in a big bowl.
3) The orange juice and olive oil should also be stirred in to from a loose paste.
4) Chicken needs to be added to the bowl and toasted to coat all over.
5) Set aside for marinating while the grill turns hot.
6) The chicken has to be grilled for 3 to 4 minutes per side. (Make sure that a thermometer shows 165 Degree Fahrenheit when you insert it into the thickest area).
7) It should be transferred to a plate and set aside for five minutes,
8) The tortillas have to be placed on the grill (you can use a skillet) and the heat has to be kept at medium to high levels.
9) When you find air pockets starts puffing up in the tortillas, they need to be turned with tongs and the other side has to be heated for a few seconds.
10) Then, the tortillas have to be wrapped in a tea towel for keeping them warm.
11) The chicken must be sliced into strips and a handful of arugula should be placed on each tortilla.
12) Each one needs to be topped with onion slices, tomatoes, radishes, sliced avocado and chicken slices.
13) Thinned sour cream has to be drizzled and can be served with lime wedges.