Preheat oven to 400 degrees F. Grate zest from lemon. Add first tablespoon of sugar, mix together and set aside. Place cranberry sauce in large strainer, break up and rinse away jelly, leaving only berries and pulp. Allow to drain thoroughly. Melt butter in a 7" iron (oven proof) skillet, and swirl pan so butter coats sides of pan. Saute drained cranberries over medium/low heat for about 3 minutes.
In the meantime, shift together flour and salt in medium bowl. Beat eggs together in a small bowl and whisk in milk. Add 1 tablespoon sugar to cranberries and heat 1-2 minutes allowing a little syrup to form. While waiting for syrup, pour egg and milk mixture slowly into flour mixture while beating. When blended, add lemon-sugar. Now pour batter on top of cranberries. Wait about a minute, then place pan in oven for 20 minutes or until set. Cut portions and serve with sprinkled confectioners' sugar and a dollop of sour cream on the top.