In a stand mixer (ideally), add your starter, water, and sea salt.  If you don't have one, you can do this by hand, but you will want to either grease or flour your hands because this will get sticky.  Start with a spoon for now.

Add your flour, about 1/2 cup at a time, with the mixer running on low.  Or, stir the flour in by hand.

The dough has enough flour when it comes together in a ball and is being kneaded rather than "stirred."  You'll see it pull away from the sides and stay together.  At this point, you will need to use your hands to knead the bread.

Knead the bread for about 10 minutes — slightly less with the machine and maybe a bit more by hand.

Shape the bread into a loaf and put it into a well-greased loaf pan.  Cut a slit about 1/2" deep down the center to tell the bread where to expand.

Allow the bread to rise at room temperature for 8 - 12 hours.  I sometimes start it around breakfast time and bake it just before dinner.  Or, I'll start it before I go to bed and bake in the morning.  This is a good project to do overnight (and if you turn the oven on first thing in the morning and then get dressed, you could have fresh bread for breakfast...even if you have to go to work), or it can rise all day while you are at work and you get freshly baked bread for dinner.  Unlike commercial yeast, it won't finish in an hour or two and then start deflating.  And it doesn't need a second rise.  It's great for busy people.

Bake at 350ºF for about an hour. Sometimes I preheat the oven, sometimes not. It's pretty forgiving; I actually think it came out with a better texture and browner crust when I put the bread into a cold oven and then turned it on   (You could let it rise in the oven, uncovered, and then simply turn the oven on without disturbing the bread at all   So easy.)

Allow the bread to cool for 15 - 20 minutes, then slice. It will fall apart a bit if you slice it while hot, but once cool, it slices beautifully and holds together. If your pan is well-greased, it should pop right out.    I often don't even wash my loaf pans if I'm going to bake again within a day because the pan is already mostly clean.