Clean and wash the spring onions. Cut off 20 centimetres long. Put cut greenery aside. Put the spring onions in an oiled, microwaveable dish. Cover and cook for three minutes at 600 watts.
In the meantime clean, wash and slice the tomatoes. Cut spring onion green into fine rings. Grate cheese. Wrap each spring onion with a slice of ham. Spread the slices of tomatoes in the dish and place the spring onions on top.
Mix the cheese and onion green and sprinkle over it. Season with salt and coarse pepper. Cover and bake for another five minutes at 600 watts.