Preheat the oven to 350°F. Line a bread pan with parchment paper, or grease it with butter followed by a layer of flour.
In a large bowl, beat the sugar and butter together for 1-2 minutes until well combined and soft. Then add in the eggs, vanilla extract, lemon zest and juice. Add the lemon concentrate if you have it. Mix together on medium speed until well combined.
Add in the flour, salt, baking soda and baking powder. Beat again on low speed until all the batter comes together. Then add your sour cream and almond milk. Mix once more just until the batter is well combined. It should still be wet with some structure, not super runny.
Pour the batter into your pan and spread out evenly with a spoon. Bake for 35-45 minutes, until the batter has set and does not appear jiggly. A knife should come out clean when inserted in the middle. The edges will have browned a bit.
To make the glaze, mix together the powdered sugar, lemon juice and almond milk. To make it thicker and sweeter, add more powdered sugar to your liking.
Once the lemon loaf is completely cool, remove from the pan. With a spoon, pour the glaze on top carefully, ensuring that the whole top is covered. Top with additional lemon slices if desired.