Mix the yeast with 1 cup warm water. Stir well to dissolve and let then rest for approx. 10 minutes.
Mix buckwheat flour, tapioca starch, rice flour, fiber husk and salt in a medium sized bowl.
Add yeast mixture, olive oil and vinegar to the flour mix, stir well for a few minutes until the dough gets thicker. Scoop even portions into the pie tins.
Place pie tins in a warm spot for approx 1 hour (or until the dough has risen twice its size).
Switch on oven to 190°C (top-/botom heat). Sprinkle the top of the buns with sesame seeds and then very gently brush with a mixture of 1 tablespoon olive oil and 1-2 tablespoon water.
Bake in the oven for approx. 15, covered with a sheet of baking paper or aluminum foul (which you can reuse). The bake another 5 minutes uncovered or until the top is golden-brown.