Prepare the Strawberry Swirl:

In a small saucepan, combine the chopped strawberries, sugar, and lemon juice. Cook over medium heat for about 5-7 minutes, stirring occasionally, until the strawberries soften and release their juices.

Add the cornstarch and stir until the mixture thickens to a jam-like consistency. Remove from heat and set aside to cool.

Prepare the Dry Ingredients:

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.

Cream the Butter and Sugar:

In a large mixing bowl, beat together the softened butter and sugar until light and fluffy, about 3-4 minutes.

Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.

Add the Wet and Dry Ingredients:

Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk. Start and end with the flour mixture. Mix until just combined, being careful not to overmix.

Create the Strawberry Swirl:

Gently fold the strawberry mixture into the batter, creating a marbled effect. Don’t stir too much—just a few swirls will give the bread its beautiful streaks.

Bake:

Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan and pour the batter into it. Smooth the top with a spatula.

Bake for 55-60 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs.

Cool and Serve:

Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely. Slice and serve.