15 Minutes Hands-On Time

1. Roast the onions – Preheat the oven to 350°F (180ºC). Rub a shallow baking dish with a little olive oil. Spread the onions in an even layer in the dish and season lightly with salt. Roast, stirring once or twice, until softened and just beginning to brown, about 20 minutes.

2. Season the fish – Meanwhile, cut the chiles in half lengthwise, then finely chop the flesh. Place the chopped chiles in a small bowl, add the adobo sauce, and stir to form a paste. Place the filets on a plate, season lightly on both sides with salt, and then rub on both sides with the chile paste.

3. Cook the fish – Arrange the filets, bone side up, on top of the onions. Bake until the filets begin to flake apart near the tail ends, 6 to 9 minutes depending on thickness. Squeeze the juice from all the lime halves over the filets and onions, garnish with the cilantro, and serve.