Mix yeast and luke warm (max 37° C / 98° F) water in a large bowl. Add salt, honey and flour, and finally the sunflower seeds. Mix it well. The dough should be soft and moist.
Cover the bowl with a kitchen towel and leave it to rise overnight (at least 12 hours). Then turn the dough 3-4 times and let it rise another couple of hours, again covered with a kitchen towel.
Now place the cast iron pan without the lid in the oven, and set the oven to 480° F.
When both the oven and the cast iron pan is hot, take out the pan and brush the inside of it with a thin layer of vegetable oil. Sprinkle a thin layer of oat meal in the bottom of the pan.
Pour the dough into the pan and place it in the middle of the oven. Let it bake for 45 minutes, but...
...put the lid on after 15-20 minutes to avoid burning the loaf. Leave a small (1/8″-1/4") so air can get out. This is what it looks like when I think it's time to put the lid on.
When it's ready, take the pan out and flip it over to get the bread out. Let it cool off for an hour or two.