Milk + Lemon Juice or Vinegar (Best Option)
1 cup milk + 1 tablespoon lemon juice or white vinegarThis substitute works because the acid (lemon juice or vinegar) curdles the milk slightly, mimicking the acidity and texture of buttermilk. The acid is essential for the tangy flavor and helps stabilize emulsions in salad dressings.
To ensure success, mix the acid into the milk and let it sit for 5-10 minutes before use. Use whole or 2% milk for best texture; skim milk may be too thin.
Compared to buttermilk, this substitute closely replicates the flavor and consistency, resulting in a dressing that emulsifies well and has the characteristic tang without being overly thick.