In large glass bowl mix together both sugars and butter with a wooden spoon. Use the back of the spoon to cream together the ingredients.
Add in egg and vanilla and now using a whisk blend together just until the egg is incorporated- about 20 seconds.
In separate small bowl whisk together the flour and baking soda.
Add all at once to the butter mixture. With the wooden spoon stir until the flour is all mixed in, then sprinkle with an additional tablespoon of flour and knead with your hands until smooth.
Add the chocolate and mix in with your hands.
Form into balls about 1½ tbsp each. Flatten slightly with the palm of your hand. Sprinkle with the sea salt. Place balls no more than 10 on a sheet so they can spread.
Bake 8 minutes, then rotate sheet and bake another 2 minutes, just until the bottoms are starting to brown and the tops appear dry but not browned.
Let cool on cookie sheet for 3-5 minutes, then transfer to cooling rack.