01 - Set the oven temperature to 400°F and line a baking sheet with parchment paper or lightly grease it.
02 - Pat the salmon fillets dry with paper towels. Brush both sides evenly with olive oil, then season with salt, black pepper, and smoked paprika if using.
03 - Place the salmon fillets on the prepared baking sheet and top each with lemon slices.
04 - Bake for 12 to 15 minutes, until the salmon flakes easily with a fork and is opaque throughout.
05 - While baking, combine diced tomatoes, finely chopped red onion, minced jalapeño (optional), chopped cilantro or parsley, olive oil, lime juice, salt, and pepper in a bowl. Gently mix to combine.
06 - Remove the salmon from the oven and allow to rest for 2 minutes before serving.
07 - Spoon the fresh salsa generously over the salmon fillets and serve immediately.