1.Cut the cod fillets into 2- to 3-inch chunks.
2.In a medium bowl, combine all the marinade ingredients: yogurt, olive oil, garlic, ginger, ground cumin, ground coriander, chili powder, turmeric, and salt.
3.Place the fish pieces in the bowl and toss them with the marinade to coat well. Cover the bowl and let it marinate in the refrigerator for 1 hour.
4.Preheat grill pan over medium-high heat. Spray with vegetable spray on top. Remove some of the excess marinade from the fish. Place the fillets spaced apart on the grill. Cook for 10 to 12 minutes, flipping the fish halfway through.
5.Serve immediately topped with cilantro and red onion.