Preheat the oven to 200C/392F.
In a medium bowl mix the flour with charcoal, salt and baking soda.
Gradually add the warm almond milk, mixing to obtain a thick batter.
Line a baking sheet with parchment paper and evenly scoop the batter to obtain two round buns.
Drizzle with olive oil, sprinkle the Nigella seeds on top and bake for 20 mins.
Remove from the oven and keep in a warm place, covered with a clean towel.
While the buns are in the oven, prepare the patties.
Add the black beans into a large bowl and crush them with a fork to obtain a chunky mixture.
Add the rest of the ingredients and mix to combine (I used my hands to mix everything well).
Shape the mixture into little patties and line them on the baking sheet.
Lower the oven heat to 175C/346F.
Bake for 15 minutes, then flip over and cook 10 minutes more.
Remove from the oven, assemble the burger and serve warm.