Combine flour, soda and salt. In separate container, beat egg until fluffy. 
In a large bowl, cream shortening, brown sugar and granulated sugar. 
Then add the beaten egg to the creamed mixture and beat well. 
Add peanut butter and vanilla to creamed mixture and mix well. 
Gradually stir in the flour mixture and blend well. With your hands, shape dough in small balls. 
Place a ball on the cookie sheet, flatten with a fork, making a crisscross on top. 
Leave space between cookies. Bake at 375° F. for about 10 minutes. 
About 4 1/2 dozen cookies.