Zest and juice oranges. Mix oil, garlic, orange zest & juice and chili powder together.
Place pork & marinade into large ziplock bag. Squeeze out air & seal.
Marinate pork 4-24 hours. I marinated for 8 hours.
Cook on broiler pan at 400 for 30-40 minutes depending on loin thicknenss & desired fondness. Mine were 2 small thin loins so I cooked for 30 minutes & they were perfect with a little pink in the middle & so juicy.