Preheat oven to 350°F (180°C). Grease and line an 8-inch round cake pan.
In a bowl, whisk flour, ground pistachios, lemon zest, baking powder, baking soda, and salt.
In another bowl, beat butter and sugar until fluffy.
Add eggs one at a time, mixing well after each.
Mix in sour cream, lemon juice, and vanilla.
Fold in dry ingredients until just combined.
Pour batter into pan and smooth the top.
Bake 30-35 minutes until a toothpick comes out clean.
Cool in pan 10 minutes, then transfer to wire rack to cool completely.