Preheat oven to 350
Line 8x8" baking pan with aluminum foil, leaving an overhang over the sides of the pan
Lightly grease foil
In food processor, process avocado, coconut oil, egg, coconut sugar, water, and vanilla
Add cocoa powder and combine until fully incorporated and free of any large lumps
Stir in flour and salt until just combined
Spread batter evenly in pan and bake for about 35 minutes, until the top has just set
Allow brownies to cool completely (about 1 hour) in the pan
Once completely cool, lift entire brownie out of pan using the foil overhangs
Remove foil from brownies and cut into 12 rectangles