Final answer:
The nurse is performing the data collection or assessment step of the nursing process by carefully entering the patient's medical history and current medication list into the electronic health record (EHR).
Step-by-step explanation:
The step of the nursing process being performed by the nurse in this scenario is data collection or assessment. By carefully entering the patient's medical history and current medication list into the electronic health record (EHR), the nurse is gathering important information about the patient's health condition. This data will be used by the nurse and other healthcare professionals to determine the appropriate care and treatment for the patient.