Slow-Roasted Salmon in Parchment Paper
2 tablespoons extra-virgin olive oil, plus more for drizzling
1 onion, thinly sliced
1 bay leaf
1 cup Castelvetrano olives, pitted, quartered
1/4 cup drained capers
1/4 cup raisins
6 tablespoons dark rum
2 tablespoons fresh lime juice
4 (6-ounce) salmon fillets, patted dry
Freshly ground black pepper
4 tablespoons coarsely chopped cilantro, divided, plus more for serving
Lime wedges (for serving)
Preheat oven to 275°F. Heat 2 Tbsp. oil in a large skillet over medium-low. Add onion, bay leaf, and a pinch of salt and cook, stirring often and reducing heat if onion is browning too fast, until onion is golden brown, 25–30 minutes.
Add olives, capers, raisins, and 2 Tbsp. water to skillet and cook, stirring occasionally, until olives are softened, about 4 minutes. Add rum and cook until liquid is evaporated, about 5 minutes. Remove skillet from heat and stir in lime juice and 1 Tbsp. water. If needed, add a splash or two more of water so mixture is saucy; season with salt.
Season salmon with salt and pepper. Cut four large sheets of parchment paper. Working with 1 sheet, spoon one-quarter of sauce onto the center of paper; scatter 1 Tbsp. cilantro over. Create a well in the sauce the size of a salmon fillet and place fish in well; drizzle with oil. Gather edges of parchment up and over salmon and tie tightly closed with kitchen twine. Set on a rimmed baking sheet. Repeat with remaining parchment paper, sauce, salmon, and 3 Tbsp. cilantro.
Bake packets until salmon is cooked through, 20–22 minutes for medium (go 2 minutes longer for well-done). Remove from oven and let salmon steam in packets 2 minutes. Unwrap and top with more cilantro. Serve with lime wedges for squeezing over.
Short on time? This sauce can be made 2 days ahead. Let cool; cover and chill. Before using, add water to loosen if it looks tight.