Step 1

Slice 3 limes in half and squeeze through a fine-mesh sieve into a small bowl (you should have about 5 Tbsp. juice); discard seeds. Cut remaining lime into wedges and set aside for serving.

Step 2

Whisk lime juice, brown sugar, soy sauce, turmeric, cayenne, and a pinch of salt in a small saucepan to combine. Bring to a boil, then reduce heat to medium-low. Cook, swirling pan occasionally to keep mixture from bubbling up, until thickened, about 8 minutes. Let caramel cool slightly (it will continue to thicken as it cools).

Step 3

Meanwhile, pat fish dry, then season with salt. Heat oil in a large nonstick skillet over medium-high. Cook fish until flesh is opaque, cooked through, and flakes easily with a fork, about 3 minutes per side.

Step 4

Divide rice among plates and top each with a fillet. Spoon warm caramel over. Top with white onion, mint, and cilantro. Serve with reserved lime wedges for squeezing over.