Using electric mixer, in a large deep bowl, beat both sugars, shortening and butter for about 5 minutes. Add the eggs and vanilla, beat for another 3 minutes until fluffy.
In a separate bowl, sift together flour, salt and baking soda.
Add dry mixture to the butter mixture and blend well with a strong wooden spoon (it is a bit hard). Add the chocolate chips and mix well. Cover the bowl with a plastic wrap and refrigerate for about an hour.
Preheat oven to 350℉.
Line good cookie sheets with parchment paper.
Pick up dough by heaping teaspoons and very lightly shape by hand into sort of messy irregular balls and drop on the sheets, not too close together. The size of the dough ball is a good guide to the distance between them.
Bake 10-12 minutes, just until they are golden. It you bake too long, they will be crispier, and not as soft.