Nice And Easy Nicoise Salad

• 4 butter lettuce leaves
• 1,200 gr microwave safe dish
• 250 gr green beans (frozen whole)
• 230 gr cherry tomatoes
• 180 ml wine vinaigrette (red)
• 2 packages tuna packed in water
• 1 slice onion (red)
• 1 package pitted ripe olives