Activating your sourdough starter Mix 1/2 cup all purpose flour, 1/2 cup plus 2 tablespoons lukewarm pure water (because impure water is just dirty), 1 tablespoon of sugar (this time only) and package of starter powder in a bowl. Cover bowl with CLING WRAP, this helps to keep the starter from drying out and forming a crust on top, and put on the counter or in a warm place if it is cold. On the second day just stir it up. On the third day add an additional 1/2 cup all purpose flour and 1/2 cup pure (there is that word again. I live in the mountains, we have great water, if you live in a city, you have crap, use filtered water) lukewarm water, stirring to mix. By 48 hours you should see bubbles and signs of life. It’s alive! Be careful to recognize if the starter is really alive at this poin.