How to make buttermilk at home

If a recipe asks for buttermilk in baking, it is easy to prepare at home.

What I need:
Milk-1 cup
Lemon juice/Vinegar-1 tsp

Makes - 1 cup

How to prepare:
To room temperature boiled milk just add lemon juice and stir. Rest it for 10 minutes. You will see curdles of milk. That's it. Done. You can straight away use them which calls for buttermilk in baking recipes.