Tirokafteri from Thessaloniki

Fry the peppers in the oil until they are tender and cooked. 

If you like, keep the frying oil. 

Peel them and throw away the seeds. 

Put the peppers in the food processor, slowly add the feta, either the frying oil or raw oil and vinegar. 

Blend until smooth. 

Taste from time to time to check on how spicy you want it to be.