Preheat oven to 150ºC . In a medium bowl, combine flour, soda, salt, and orange peel. Mix well with a wire whisk and set aside. In a large bowl, blend sugars with electric mixer at medium speed. Add butter and beat to form a grainy paste, scraping sides of bowl if needed. Add eggs and orange extract, and beat at medium speed until light and fluffy. Add the flour mixture and chopped chocolate. Blend at low speed just until combined. Do not overmix. Drop by rounded tablespoons onto an ungreased cookie sheets, 3 cm apart. Bake for 22-24 minutes until cookies are slightly brown along edges. Transfer cookies immediately to a cool surface with a spatula. Makes 3 dozen.