With regard to the Hermita I very much doubt that you would find them on the internet but I am surprised that the buffet in Amposta is not.  I might be worth googling gran buffet japones / mediterranso.

The hermita is in Tortosa.  If you don't know how to get to the hospital follow the signs to l'hospital verge de la cinta from the roundabout on the north side of the Millenium Bridge.  At the roundabout where you turn right to the hospital carry straight on up the hill.  We knew that it must be good when we went in and found it full of locals come up from the town for their lunch.  I don't know but I would think that it doesn't open in the evenings or on Sundays.  We shall be up there again celebrating another wedding anniversary on 2nd April so I will try and find out more about opening hours then and post on the forum.