Wash the squid very well. Remove the cartilage on the inside because it tastes unpleasant. Some people don't remove it but I find it absolutely necessary.
Put the grill pan to heat up well. Put squid slices in it, as many as the pan will fit.
Don't put all of the squid slices in at once because part will remain raw if you do. Once they gain a slight crust, flip them over. Repeat until every slice is cooked.
Serve with lemon.