Preheat oven to 400°F. Butter a 10" cast iron skillet with 1 tablespoon of the butter.
In a large mixing bowl, stir together the flour, salt, baking soda, and seeds. Make a shallow well in the center of the bowl and pour in 1 1/2 cups of the buttermilk. Stir with a wooden spoon, incorporating all of the flour into the buttermilk. Add more buttermilk a tablespoon at a time, if necessary, until the dough comes together (but don't overwork).
Turn out the dough onto the counter. It will be craggly, stringy, and slightly sticky. Wet both hands, and gather up the dough and knead quickly into a flattened disk. Divide the dough in 5 or 6 more-or-less equal pieces, and work each into a ball. Arrange the dough balls in the skillet, without packing too tightly.
Bake for 15 minutes. Meanwhile, melt the remaining butter in a small pot. At the 15 minute mark, the tops should begin to brown. Remove and brush each roll with the melted butter. Return to oven and bake for 5 to 10 minutes more. The minis will be golden with browned peeks. Remove, and let rest a bit before serving, or until they can be handled.
Split open and slather the insides with more butter. Inhale the baked bread goodness, and enjoy.