In a medium-sized bowl, mix together the honey, soy sauce, garlic, toasted sesame oil, Chinese five spice, and a pinch of chili flakes.
Place the rainbow trout fillets into the bowl with the honey-soy mixture, and make sure they are well coated. Cover the bowl, place it into the fridge, and leave the rainbow trout to marinade for at least 2 hours.
Preheat the oven to 350 F, transfer the rainbow trout fillets to an oven-proof dish, and bake for 10 to 12 minutes, until the fish is cooked though and flakey.