Preheat oven to 350ºF. Lightly spray or grease and flour an 8×4 inch loaf pan. Set aside. Toast the pecans in a dry skillet over medium-high heat for a couple minutes. Do not step away or you will burn the nuts – trust me on this! Whisk together the flour, baking powder, baking soda and salt in a large bowl. Make a bit of a well in the center and set aside. In a medium bowl, mix the sugar and lemon zest. Add the buttermilk, lemon juice, eggs, vanilla, butter, and mix. To the center well in the dry ingredients, pour in the liquid ingredients, mixing gently to combine. Do not over mix. Gently fold in the blueberries – if you are using frozen, make sure to not thaw them – they will hold up better. Fold in the pecans. Pour batter into the prepared loaf pan and bake for about 60 minutes or until a tester inserted in center comes out clean. Cool in the pan on a rack for 20 minutes. After the 20 minutes is up, remove from the pan and cool to room temperature. To make the glaze, in a small saucepan, combine the sugar and lemon juice. Bring to a boil and then reduce to a simmer, stirring (or swirling) until the sugar is dissolved and it’s a bit syrupy. Brush the glaze over the bread while it is still warm.