Cut the leeks in half lengthwise, then into quarters and wash thoroughly. Trim any woody ends from the asparagus.
Brush the leeks and asparagus with the olive oil and cook on a hot grill pan over a medium high heat until tender. Transfer to a serving plate.
Toss the butter beans with 1 tablespoon of the oil and cook over a medium heat for 5 minutes or until heated through.
Spoon the butter beans over the asparagus and leeks.
Combine the almonds and Parmesan in a small bowl, sprinkle over the beans and drizzle with the combined balsamic and remaining oil.
Add the tuna and season to taste.