The night before: 

1. In a large bowl, place all the ingredients for the levain and stir until combined. 
2. In a medium bowl, place the sunflower seeds and cover with boiling water to about 1/2 inch above the seeds. 

The next morning: 

1. Cut parchment paper into a rectangle to fit in the bottom of a 10x5x3 1/2 inch loaf pan (It could have different dimensions, but it must fit 2 liters, or 8.5 cups). Liberally oil and flour your pan, including top edges and the bottom parchment paper.
2. Drain the soaked seeds and add to the levain, along with all the other ingredients under “for the loaf.” 
3. Mix until well combined. The batter should be wet and very sticky like the dough for a quick bread. 
4. Place the dough in the prepared loaf pan and smooth out the top. Dust with some rye flour. 
5. Let the dough rest until it rises just above the top of your pan. It should rise about 1/3 larger in size. The surface will crack, and you might see 5-10 pinholes on top of the loaf. This should take between 1 1/2 and 3 hours. 
6. 30 minutes before you’re going to make it, preheat the oven to 465 Fahrenheit. 
7. Put your bread in the oven and immediately turn the oven down to 450 Fahrenheit. 
8. Cook your bread between 40 and 70 minutes. You’ll know it’s done when it reaches an internal temperature of 208 Fahrenheit. If you don’t have a thermometer, stick a skewer into the middle and all the way to the bottom. It’s done when the skewer comes out dry. 
9. Remove your bread from the pan right away. If you can’t remove it for some reason, don’t yank it out. Just let it cool a bit and then it should come out of the pan easily after running a knife around the edges. 
10. When your bread has cooled, place it in a plastic bag and let it sit for 24 hours before slicing. 
11. Enjoy as the base of an open-faced sandwich or by itself.