In a small bowl, whisk the chia seeds in a cup of water. Set aside for at least 20 minutes.
In a larger mixing bowl, combine the buckwheat flour, baking powder, salt and sunflower seeds. When the chia mixture is ready, add it into the flour mixture along with ⅔ cup water and olive oil. Mix until combined. Let rest for 10 minutes.
Preheat oven to 355F.
Lightly grease a loaf pan and line it with parchment paper. Pour in the dough and sprinkle sunflower seeds on top.
Bake for at least 1 hour and 10 minutes or until edges are slightly browned and a toothpick inserted into the loaf comes out clean.
Allow the loaf to cool for 10-15 minutes before removing from the pan.