In a large mixing bowl, combine the oat flakes, salt, and baking soda. Stir to combine.
Gradually add water to the dry mixture, a little at a time, until you get a dough-like consistency. Be sure not to add too much water—aim for a thick batter.
Stir in the mixed seeds and make sure they're evenly distributed throughout the dough.
Transfer the dough to a loaf pan lined with parchment paper or lightly greased.
Preheat the oven to 180°C (350°F) and bake for 25-30 minutes, or until the top is golden and the bread is firm to the touch.
Once done, let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely. Slice and serve.