How to Make It
Preheat oven to 350 degrees F.
Weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour, granulated sugar, 1 1/2 teaspoons matcha, baking powder, baking soda, and salt. Combine buttermilk, 1/4 cup water, butter, rind, and egg, stirring with a whisk. Add buttermilk mixture to flour mixture, stirring until combined.
Coat 2 (6-cavity) donut pans with cooking spray. Spoon batter evenly into 12 cavities. Bake at 350°F for 12 minutes or until donuts spring back when lightly pressed. Cool in pan for 2 minutes. Run a thin knife around outside edge of each cavity; invert donuts onto a wire rack. Cool completely.
Combine powdered sugar, remaining 4 teaspoons water, remaining 3/4 teaspoon matcha powder, and lemon juice, stirring until smooth (add more water, 1/2 teaspoon at a time, if glaze is too thick). Spread glaze over tops of donuts; sprinkle 6 donuts evenly with coconut and 6 with goji berries. Let stand until glaze is set.