Start with a couple of cloves fresh garlic -I like a lot of garlic, but if you are a bit shy in this area, you can start with just one. Smash the garlic by pounding your fist against the flat blade of the knife (yeah, that's how real chefs do it, no garlic press needed!). Sprinkle the garlic with some sea salt - the sea salt has a nice big grain which helps. Using the flat of the knife and the palm of your hand, mash the garlic and salt until it forms a paste. It takes a few minutes. Have patience. Enjoy the smell. Do NOT be tempted to resort to chopping the garlic at this point - it will wreak havoc on a knife blade with all that salt. When you have a good paste, transfer the garlic to a bowl. Spoon in equal parts mayonnaise and sour cream and stir to combine.
Now, slowly whisk buttermilk into the mixture until you reach your desired consistency. Do a taste test to determine if you want more sour cream - I usually do. Grind some pepper and add more salt if needed. Now, you can stop here, or you can finish it off with some chopped herbs - preferrably a nice helping of dill and maybe some parsley as well?
Stored in a jar in the frig, it will keep for a couple of weeks.