In a small bowl, whisk together the lime juice, orange zest, cumin, smoked paprika, oregano, garlic powder, onion powder, salt, black pepper, and olive oil to make a marinade. Rub the marinade all over the lamb ribs, cover, and refrigerate for at least 4 hours or overnight.
Prepare a braai for indirect cooking by banking up the coals on one side so that there is a hot side and a cooler side.
Place the lamb ribs on the cooler side of the braai with the bone side down. Cover with a lid and adjust the air flow to 1/4 open at the base and leave a small crack (2mm) in the vent holes on the lid. This will ensure the coals burn slowly and evenly. Braai for 2-3 hours, turning every 30 minutes, until the ribs are tender and the meat is falling off the bone.
While the ribs are cooking, make the mojo sauce. In a small bowl, whisk together the lime juice, orange juice, garlic, cumin, oregano, olive oil, salt, and black pepper.
Serve the braaied lamb ribs with the mojo sauce on the side. Enjoy!