Peel and roughly chop the onion. Core the cucumber (otherwise the dip will be too runny) and roughly chop it too. Peel the garlic and put everything in a blender along with the feta and cream cheese. Mix coarsely or creamy depending on your taste. Then season everything with salt (attention: the feta has a lot of flavor!) And pepper to taste.
Tip: If vegetables are dipped, add a little salt, as the unsalted vegetables can otherwise make the taste bland.