This is a simplified version, so know it won't be as complicated as other focaccia recipes you may have seen. This is to make it a recipe anyone can make.
Add the water, starter, and salt to a bowl. Mix well, then add in the flour. Mix this until all the flour is incorporated. You can do this with your hands or with a spoon.
Cover and let this rest for 30 minutes to an hour.
Now you will begin a series of 3 stretching and folding.
Pour the dough onto your surface. This dough will be sticky, if you aren't used to working with tacky dough, sprinkle just a touch of flour on the surface. Gently stretch the dough to a large oval.
Now start pulling the dough back in on itself. You can see this in the video. Once it is pulled in, gently knead as shown in the video.
Place back in the bowl and cover. Let this rest for 30 minutes and repeat the process 2 more times.
It is time for bulk fermentation. Cover the bowl and let it rise until it has risen about 30-40%. Mine took 2 hours in a 74-degree house.
Once it has risen, place it in the fridge for an overnight chill. This can be 12-224 hours. It should have also risen in the fridge. You will see bubbles have formed just under the surface.
When you are ready the next day, spray your pan with pan release or butter it. Then add in about ⅓-1/2 cup olive oil.
Gently turn out the dough onto the pan. Drizzle another ¼ cup of olive oil over the dough.
Cover and let this rise at room temperature for 4-6 hours. The dough should be very bubbly and jiggly.
Preheat the oven to 425 degrees. Drizzle more olive oil over the surface and sprinkle with the sea salt. Gently dimple the dough with your fingers. You can see this in the video.
When the oven is ready, place the focaccia in the oven. If you are baking on a sheet pan, it will take about 20 minutes. In a 9x13 pan, it will take about 25 minutes. It should be a beautiful golden brown.
Remove it from the oven and let it cool for about 10 minutes.