Preheat oven to 325 degrees F. Take some of the butter and lightly coat a 13 by 9-inch glass baking dish.In one large bowl, mix together flax meal, salt, buckwheat flour and walnuts. Beat eggs in a separate large bowl.Place chopped chocolate in a third glass or metal bowl over boiling water to melt. When chocolate is roughly half melted, add honey, cocoa powder, butter, and vanilla and continue to slowly stir until all of the chocolate is melted. Remove chocolate from heat and pour half into the beaten eggs while stirring the eggs to temper them. Once this is fully mixed, add the rest of the chocolate to the eggs and continue to stir until a smooth consistency. Pour the new chocolate mixture into the dry ingredients and mix thoroughly.once the batter is fully mixed you want to have it in the oven within the next 3 minutes. Dissolve the baking soda in the 2 tbsp of water and pour over the brownie batter. Quickly stir and spread out batter in the prepared baking dish.