Preheat oven to 350°F. In a standing mixer fitted with the paddle attachment, cream together the coconut oil, avocado, and maple syrup until smooth.
In another bowl, whisk together the teff flour, almond flour, cacao powder, baking powder, and sea salt. Mix the wet ingredients into the dry. Stir in the dark chocolate chips, cover the batter, and let chill in the fridge for at least 30 minutes.
Scoop heaping tablespoons of dough onto a parchment-lined baking sheet and press down with wet fingers. Sprinkle each cookie with a pinch of flaky sea salt, and bake in the oven for 10-12 minutes. Remove from the oven and let cool.