Preheat oven to 350°F.
Gently toss blackberries in a bowl with 1 tablespoon of flour (this will keep them from sinking to the bottom of the batter while baking).
Using a stand mixer or a handheld electric mixer, cream butter and sugar.
Next, add eggs one at a time, mixing well after each.
Once the eggs are well blended into the batter, add yogurt, milk, and lemon juice, and mix again.
In a separate bowl, stir together the flour, salt, and baking powder.
Add dry to wet ingredients and mix until thick and smooth.
Finally, using a spoon or rubber spatula, fold in lemon zest and blackberries.
Grease a loaf pan with vegetable shortening and pour batter into the pan, leveling the top with a rubber spatula.
Bake for 50 to 60 minutes or until a toothpick inserted in the center comes out clean.
Let cool completely on a wire rack before adding lemon glaze. If you add the lemon glaze while the lemon blackberry bread is still hot, it will soak in instead of staying on top.
In a small bowl, simply whisk together powdered sugar, lemon juice, and lemon zest.
Pour over completely cooled lemon blackberry bread and garnish with extra blackberries and lemon zest.
Enjoy with or without lemon glaze, with a tall glass of lemonade or a cup of tea or coffee, or with a scoop of ice cream for dessert!