Preheat the oven to 180°C with fan circulation or 200°C with top and bottom heat. Line a baking sheet with parchment paper. Pat the salmon fillet dry with paper towels. Break off the tough lower ends of the green asparagus and rinse the stems under the tap.
Place the salmon fillet and asparagus next to each other on the baking sheet. Pour the olive oil over the fish and vegetables. Sprinkle with a pinch of sea salt and freshly ground black pepper. Cut a few slices of lemon and place them on the salmon. Squeeze the rest of the lemon over the asparagus.
Slide the baking sheet into the oven and bake the salmon and asparagus for 12 to 15 minutes until cooked. The dish is ready when the fish easily flakes apart with a fork and the asparagus has a slight bite to it.
Remove the baking sheet from the oven and let the ingredients rest for one minute. Transfer the salmon and asparagus to a plate. Drizzle the whole dish with the remaining liquid from the olive oil and the lemon juice from the baking sheet and serve immediately.