In a small bowl, whisk together the olive oil and balsamic vinegar. Brush the mixture over both sides of the tuna steaks, then season generously with salt and pepper.
Air fryer method: Preheat to 180°C (350°F). Place the tuna steaks on the rack and cook for 8 minutes, turning halfway through. Top each steak with a slice of Stilton and cook for an additional 2 minutes, until the cheese starts to melt.
Griddle pan or non-stick pan method: Heat over medium-high heat. Sear the tuna steaks for about 3 minutes per side. Reduce heat to low, add the Stilton slices on top, cover with a lid, and cook for another 2-3 minutes until the cheese softens and melts slightly.
Note: tuna is best served slightly pink in the centre for tenderness, so avoid overcooking!
Serve the tuna steaks immediately with your chosen side dish.
Drizzle with extra balsamic glaze for a gourmet touch!