Remove the seeds from the peppers, put in a blender and blend until fine. Add the yoghurt and make 2-3 swirls with a knife. Crumble the feta cheese and add it in, beat until the feta cheese breaks up into small granules.
Pour the mixture into a bowl, pour the olive oil in a trickle while stirring nonstop with a spatula until the olive oil is well absorbed. You can store the tirosalata in a food container with a lid in the fridge.
This appetizer is also known by other names - tirokafteri, tirohipiti - but they're all one and the same.