Melt the butter in a large microwave-safe bowl. Add the sugar and orange juice concentrate, and stir. Let the mixture cool slightly. Add the eggs, baking soda, salt, and orange zest, stirring after each addition. Add the flour in increments and mix thoroughly. Cover the bowl and refridgerate the dough at least 2 hours (overnight is even better).
When you're ready to bake, preheat the oven to 350, withthe rack in the middle position.
Roll the chilled dough into walnut-sized balls . Put 1/3 cup of white sugar in a small bowl and roll the balls in it. Place them on a greased cookie sheet. press the balls down slightly so they won't roll off the sheet.
Bake at 350 for 10-12 minutes. the dough balls will flatten out all by themselves. Let the cookies cool for 2 minutes on the sheet and then move them to wire racks to finish coooling.