When the aubergines have eliminated all the vegetation water, cut the spring onion into thin slices. Pour the oil into a pan, let it heat and add the spring onion. Once it is golden brown, add the aubergines and let them cook for about 4 minutes. In the meantime, wash the cherry tomatoes and cut them into 4 segments and add them to the aubergines. Season with salt and leave to cook for another 4-5 minutes. Meanwhile, cook the medallions in plenty of salted water. After 2 minutes, add the medallions to the aubergine sauce and serve hot.