Paint with butter and flour a deep round mould.
Place the puff pastry sheet in the mould with its borders hanging over the mould edge. Prick the bottom with a fork and paint with beaten egg.
Preheat the oven to 200ºC.
Meanwhile, in a frying pan shallow fry in olive oil the young garlics and the leeks. Set aside, oil drained.
Place a layer of tomato slices onto de pastry. Sprinkle with half the minced garlic and dried oregano.
Over this layer put the young garlics and leeks we had set aside, and cover with another layer of tomato slices, minced garlic and oregano.
Finally, cover with the grated cheese.
Fold the borders to partially cover the vegetables and paint with egg.
Bake for around 25 minutes (200ºC)
Serve warm or lukewarm.