Preheat oven to 325°F (160°C). Spray a 9x5-inch loaf pan with nonstick cooking spray containing flour.
Sift together flour, baking powder, and salt in a medium bowl. Whisk sour cream with lemon juice in a small measuring cup.
In the stand mixer bowl, rub lemon zest into sugar until moist and fragrant.
Add butter and beat on medium until pale and fluffy, about 3-4 minutes. Scrape bowl as needed.
Add eggs in three additions, beating well after each and scraping bowl as needed.
With mixer on low, alternately add dry ingredients in three additions and sour cream mixture in two additions, starting and ending with dry ingredients.
Scrape bowl and beat on low 30 seconds; ensure batter is uniform.
Transfer batter to pan, smooth top, and tap to release air bubbles.
Bake 55-65 minutes until a thin knife inserted comes out with few moist crumbs.
Cool 10 minutes in pan, then turn out on wire rack.
While baking, combine sugar and lemon juice for syrup in a small saucepan.
Heat over medium-high, stirring until sugar dissolves, simmer 2 minutes, then remove from heat.
Brush warm cake top and sides with syrup, using all syrup. Cool completely about 2 hours.
To make glaze, stir confectioners sugar and lemon juice until smooth.
Pour glaze over cake, cover completely, and let set 15 minutes before serving.
