Preheat the oven to 350°F.
Butter and flour a 8½ by 4½ inch loaf pan.
Sift or whisk together the flour, baking powder, baking soda, and salt in a medium sized bowl.
1½ cup (200 grams) all-purpose flour, 1 teaspoon baking powder, ¼ teaspoon baking soda, ¼ teaspoon salt
Cream the butter, sugar, and lime zest together until light and fluffy. If using a stand mixer, this will take about 5 minutes on medium speed, longer if using a hand mixer.
8 tablespoons (113 grams) unsalted butter, 1¼ cup (250 grams) granulated sugar, zest of 2 limes
Add the eggs one at a time, beating for a minute after each addition and scraping down the bowl as necessary.
2 large eggs
Add approximately one half of the dry ingredients and mix on low speed until they are just incorporated.
Add the buttermilk and lime juice and beat until mixed. Scrape down the bowl.
¼ cup buttermilk, ¼ cup lime juice
Add the remaining dry ingredients and mix until just barely incorporated.
Pour the batter into the prepared pan, even out the batter and give the pan a few thwacks on the counter to remove any air bubbles.
Bake for about 50 to 60 minutes until the top has started to brown and a toothpick inserted into the center comes out with just a few moist crumbs. Check the loaf cake after about 30 or 40 minutes and cover it loosely with aluminum foil if it is starting to brown.
Cool in the pan for 10 minutes, and then invert and transfer to a cooling rack.