I applied online. The process took 4 weeks. I interviewed at European Commission (Sevilla, Sevilla, Andalusia) in Jan 2018
Interview
Application was submitted in a open call that leaves your curriculum in a pool. Afterwards when needed you are contacted and asked about your interest in any available position. If you accept you are offered a interview. This is made on site and traveling expenses are paid. First you do a 1h webased test and after you go in an interview that focus on the tasks of the job.