Preheat the oven to 350F (175C). Lightly coat a loaf pan with 1 tsp of vegetable oil, set aside for later use.
Sift together AP flour, baking powder, and baking soda. Then add salt to the sifted flour mixture (Kosher salt is too coarse, it can't be sifted).
Coat pieces of bananas with lemon juice, then put them in a mixing bowl of a stand mixer fitted with the paddle attachment; and mix on low speed until the bananas have a puree-like texture. Approximate 1 minute.
Combine egg, sugar, and oil and add them to the mixing bowl and mix on medium speed until blended, about 30 seconds. Scrape down the bowl as needed.
Add the flour mixture and mix until everything is just combined, about 15 to 20 seconds. Scrape down the bowl as needed. Don't overmix the batter.
Pour the batter into a prepared loaf pan. Use a spatula to smooth out the top of the batter. And gently tap the pan or pick it up just 1-2 inches away from the counter and drop it down to burst any large air bubbles.
Put in the oven and bake until the bread springs back when pressed and a toothpick inserted near the center comes out clean, about 45 minutes.
Cool the bread in the pan for a few minutes, then unmold it onto the baking rack and cool completely before serving.