Grate cheese and onion and blend with rest of ingredients.
Notes from Gay: That was the original. I add garlic, of course - 1 or 2 cloves. If I don't have buttermilk, I replace it with yogurt or cottage cheese. If it's too thick, thin with milk or sour creme or whatever. I don't bother grating. I put it all in the mini food processor and mix. It separates if it stays in the fridge too long but does better if made with yogurt.