1/2 cup all-purpose flour
1/4 cup wheat germ or whole-wheat flour
1/2 teaspoon kosher salt
1/4 teaspoon baking soda
2 ripe bananas
1/2 cup granulated sugar
1/4 cup vegetable oil
1/4 cup plain yogurt (not Greek)
1/2 teaspoon pure vanilla extract
1 large egg
1 to 2 tablespoons turbinado sugar, optional
Spray a 7-inch round air-fryer insert, metal cake pan or foil pan with nonstick spray. Set aside.
Whisk together the flour, wheat germ, salt and baking soda in a medium bowl. Mash the bananas until very smooth in a separate medium bowl. Add the granulated sugar, oil, yogurt, vanilla and egg to the banana and whisk until smooth. Sift the dry ingredients over the wet and fold together with a spatula until just combined. Scrape the batter into the prepared pan and smooth the top. Sprinkle the top of the batter with the turbinado sugar if desired, for a crunchy, sweet topping.
Put the pan in a 3.5-quart air fryer and cook at 310 degrees F, turning the pan halfway through, until a toothpick inserted in the middle of the bread comes out clean, 30 to 35 minutes. Transfer the pan to a rack to cool for 10 minutes. Unmold the banana bread from the pan and let cool completely on the rack before slicing into wedges to serve.