Milk + Lemon Juice or Vinegar (Best Option)
1 cup milk + 1 tablespoon lemon juice or white vinegar (let sit 5-10 minutes)This substitute works because the acid from lemon juice or vinegar curdles the milk slightly, mimicking the acidity and texture of buttermilk. The acidity helps weaken gluten strands in the dough, resulting in a tender and flaky crust. The moisture content remains similar to buttermilk, ensuring proper dough hydration.
For best results, use whole or 2% milk and allow the acid to fully react with the milk before adding to the dough. Avoid using skim milk as it may reduce tenderness. Mix gently to avoid overdeveloping gluten.
Compared to buttermilk, this substitute yields nearly identical texture and flavor in the pie crust, maintaining the delicate balance of moisture and acidity necessary for optimal flakiness.