Preheat the oven to 400 degrees F.: The warmth in the kitchen will be filled with a low, anticipatory heat, and the oven set to 400 degrees F gives the right balance for caramelizing the pineapple while cooking the salmon through. Preheating ensures the surface sizzles quickly rather than slowly steaming. You want the oven fully hot before the pan goes in, otherwise you may lose the glossy glaze finish. A common mistake is not waiting for a full preheat which leads to a pale exterior and uneven cooking.
Line a baking sheet with foil and lightly grease it with cooking spray or olive oil.: The foil helps with cleanup and reflects heat so the bottoms of the pineapple and salmon brown more evenly. A thin coating of oil prevents sticking and encourages caramelization where the glaze touches the surface. When the sheet enters the oven you should hear a faint hiss as the oil warms, and the foil will shine. Avoid using too much oil which can pool and interfere with browning.
In a small bowl mix the Sauce ingredients.: As you stir the sweet chili sauce , grated ginger , minced garlic , brown sugar , oyster sauce , fish sauce , soy sauce , and lime juice the aromas will unfold, with sharp ginger and garlic cutting through sticky sweetness. This mixture should look glossy and slightly pourable, with a balance of sweet and umami. Taste a tiny amount to check balance but be mindful of strong salt from the fish sauce and soy sauce . Overmixing is not an issue, but letting it sit too long can mute the fresh bite of the ginger .
Arrange the pineapple slices or rounds in a single layer on the prepared baking sheet.: Lay the pineapple so each slice sits flat and there is space between pieces for air to circulate. You should see edges beginning to glisten as natural juices settle on the foil. Proper spacing allows the fruit to caramelize and prevents steaming. Crowding will trap moisture and produce soggy rings instead of crisped edges.
Place the salmon on top and brush with the sauce mixture.: Gently nestle the deboned salmon over the pineapple and brush the surface with the sauce so it forms a shiny coat. The brush strokes will leave a lacquered finish that starts to thicken in the oven, and the sugar will begin to brown around the edges. Ensure the flesh has been patted dry first so the glaze adheres. If the fish is too wet the sauce will slide off and you will lose that glossy cling.
Bake for about 15 minutes or until just cooked.: In the oven you will notice the sauce bubbling gently and a sweet steam rising as the pineapple caramelizes. The salmon should be opaque and flake easily with a fork when done, while the surface keeps a tender sheen. Check the thickest part after 12 minutes to avoid overcooking, as salmon becomes dry if left too long. A usual error is relying solely on time rather than visual cues, so always test the flesh for doneness.
Squeeze some lime juice on top, and garnish with chopped peanuts, cilantro, and green onions.: The finished dish benefits from an immediate squeeze of fresh lime juice which brightens the glaze and accents the tropical notes. Scatter the chopped peanuts for crunch, then add the cilantro and green onions for herbal lift and a pop of green color. The contrast in textures and aromas at this point is delightful, and the citrus will smell citrusy and sharp. Avoid adding these garnishes before cooking, or they will wilt and lose vibrancy.
Serve with lime slices.: Serving with extra lime lets everyone finish their plate to taste. The tart juice contrasts with the sticky glaze and refreshes the palate between bites. Presenting lime slices is practical and visually appealing, and it invites diners to customize acidity. A misstep is over-squeezing all the lime ahead of time which can overwhelm the flavors.