Actually, the 'Palpís' (mind the accent) is a stuffed leg of lamb. Here is a picture with the corresponding recipe:

http://www.lleidatur.com/pic//pdf/aralleida31/receptes.pdf

What I am surprised about it the 'a la plancha' part. Stuffed meat usually takes it time, and leg of lamb is typically roasted or simmered at quite low heat in the oven, not grilled at high heat.