“Make sure the buttermilk for your biscuits is cold. Buttermilk adds tenderness as well as a tangy flavor. If you do not have buttermilk available, you can make your own by starting with 1 tablespoon lemon juice or vinegar and enough milk to equal 1 cup. Let stand 5 minutes.”
This tip is from Land O Lakes – more can be found here: https://www.landolakes.com/expert-advice/10-tips-for-perfect-buttermilk-biscuits/