Cut the feta into small cubes, peel and press the garlic - puree both together. Depending on the taste and spreadability, add the sour cream and olive oil, season with salt and pepper.
Tastes great on freshly baked bread or for grilling, but you can also fill turkey steaks with it.
You can still vary it: e.g .: puree sun-dried tomatoes in oil, season with pesto.