Preheat the oven to 375 degrees F. Line a baking sheet with parchment paper.
Whisk together the sweet chili sauce and coconut milk.
Place the salmon on the prepared baking sheet and season with salt and pepper. Brush 1 tablespoon of chili sauce mixture on the salmon; reserve the remaining sauce for serving. Roast the salmon until firm and cooked through, about 15 minutes.
Meanwhile, peel and dice the mango into 1/2-inch pieces. Dice the bell pepper into 1/4-inch pieces. Slice the mint leaves into thin strips. Divide the mango, bell pepper, mint, bean sprouts, and peanuts and lettuce leaves between individual bowls or plates for serving.
Once the salmon is cooked, use a fork to flake apart the flesh. Divide between the plates or bowls; let diners build their own lettuce cups with the lettuce leaves.