Spread the puff pastry out. Cut it into rectangles of the desired size. Smear each piece lightly with a little mayonnaise / mustard, or a mix of both.
Do not overdo it - smear just enough to lightly cover up to the edges. Crumble the feta cheese and mix it with 1 egg.
Season the filling with salt, pepper and savory. Distribute some of it onto each piece of puff pastry.
Close the pastries by gently pressing their edges together. Make light cuts with a knife along the surface of each.
Smear the top with the egg beaten with a little oil.
Arrange them in a tray with baking paper and bake in a moderate oven, until they turn rosy.