Tried a super simple Vietnamese marinade last night and it was delicious:
3 T cilantro, minced
2 cloves garlic, minced
3 T fish sauce
1/2 T Agave nectar (or 1 T of sugar)
Combine in zip top bag and marinate filets for 15-30 min. Sear over Med-High heat in oiled pan 4 min each side, or until fish flakes.