1/4 cup mayonnaise (not low-fat, preferrably homemade)
1/8 cup sour cream (not low-fat)
1 clove garlic
1 tsp. white vinegar
Buttermilk to thin
Mince the garlic with a knife, sprinkle with salt and mash into a paste with a fork. In a bowl combine mayo and sour cream. Add seasonings. Add vinegar. Add buttermilk to taste and to thin to preferred consistency. Adjust seasonings to taste. Taste it with a carrot or on some lettuce to get the right strength.
The versions of Ranch I have made most recently still have fresh chives and parsley in it thanks to some plants in my kitchen bay window. I hope to be able to keep them alive through the winter because the fresh taste makes all the difference in the dressing. I use about 5-6 straws of chive and about 5-6 "leaves" of parsley but that is totally up to your taste buds. Experiment and adjust. And although I made the first few batches of ranch without the buttermilk, it makes a huge difference to have buttermilk in it. I will never go without again!!!