Preheat oven to 350 degrees F.
Grease a 9x5 inch aluminum loaf pan with butter. Set aside. Optional: For cleaner release, you can line the pan with parchment paper with overhang on the sides.
Mix the dry ingredients: In a medium bowl, whisk 2 cups all-purpose flour, baking soda, and salt until evenly combined.
Mix the wet ingredients: In another large bowl, mix the egg, granulated sugar, vegetable oil, buttermilk, vanilla extract, and lemon zest until evenly combined.
Gradually, add the dry ingredients to the wet ingredients, whisking until no pockets of flour remain. Do not overmix.
Thoroughly pat dry the diced strawberries. Reserve about 3 tablespoons of strawberries for later and set aside. Toss the remaining diced strawberries with 1 ½ tablespoons all-purpose flour. Gently, fold in the flour-coated strawberries into the batter until just combined, leaving any excess flour behind.
Pour batter into the prepared loaf pan. Top with the reserved 3 tablespoons of diced strawberries, gently pushing them down into the batter but letting them still be visible. This will make the bread more beautiful.
Bake for about 60-65 minutes, or until a toothpick inserted in the middle comes out clean. About 40 minutes into the baking time, cover with aluminum foil to prevent it from browning too fast. Tip: To prevent the bread from sinking in the middle, only open it once when you need to cover it with foil, and when it’s ready to check for doneness.
Remove from oven and let it cool for 20 minutes before removing from the pan. Then, carefully remove from the pan and let it cool a bit more before slicing. Note: The strawberries inside may look a little bit pale, that’s normal. Using bright red and firm strawberries helps with that.