Prepare a grill or grill pan. Season both sides of the chicken with spice rub, salt and pepper. Brush the chicken breasts on both sides with olive oil. Grill skin side down, until well-browned and cooked through, about 8 minutes on each side.
While the chicken is cooking, make the salad. Combine the corn kernels, arugula, and oregano in a bowl. Add desired amount of citrus vinaigrette, toss, and season with salt and pepper. With a vegetable peeler, shave the pecorino onto the salad. Toss lightly.
Slice chicken into bite size pieces, place on top of salad and serve.
Toast the fennel seeds, coriander seeds, and peppercorns in a small, heavy pan over medium heat. When the fennel turns light brown, work quickly and add the red pepper flakes, and toss. Immediately turn the spice mixture out onto a plate to cool. Put mixture in a blender with the chili powder, salt, and cinnamon and blend until the spices are evenly ground. If you have a small spice mill or a coffee grinder dedicated to grinding spices, grind only the fennel, coriander, pepper, and chili flakes. Pour into a bowl and toss with the remaining ingredients. Keep the spice mix in a glass jar in a cool, dry place, or freeze.
Cut off and discard the stem ends of 2 oranges. Cut into quarters, cut out the core, and pull out seeds. Place in a blender or food processor. Squeeze the juice from the remaining orange into the blender and add the red onion, sage, salt, and pepper. Pulse and then blend the fruit until as smooth as possible. With the machine running, add the olive oil in a thin, steady stream. The vinaigrette will be thick like a mayonnaise. If it is too thick, with the machine still on, thin with a little warm water. Taste for seasoning. Cover and refrigerate for up to 3 days. If the vinaigrette separates, shake it up in a jar or return it to the blender and blend until smooth again.