01 - Preheat oven to 350°F. Grease and flour a 9x5-inch loaf pan or line it with parchment paper.
02 - In a small bowl, combine flour, sugar, lemon zest, and cold butter. Work the butter in with fingers or a pastry cutter until coarse crumbs form. Refrigerate until needed.
03 - Whisk together flour, baking powder, baking soda, and salt in a medium bowl. Set aside.
04 - Beat softened butter and sugar in a large bowl until light and fluffy, about 2 to 3 minutes.
05 - Add eggs one at a time to the butter mixture, beating well after each addition. Then mix in milk, lemon juice, lemon zest, and vanilla extract until combined.
06 - Gradually add the dry ingredients to the wet mixture, stirring just until incorporated.
07 - Gently fold fresh or frozen blueberries into the batter without overmixing.
08 - Pour batter into prepared loaf pan and smooth the surface. Evenly sprinkle the streusel topping over the batter.
09 - Bake for 50 to 55 minutes or until a toothpick inserted into the center comes out clean. Tent with foil during the final 15 minutes if top browns too quickly.
10 - Let the bread cool in the pan for 15 minutes, then transfer to a wire rack to cool completely before slicing.