You must request your Dean's Letter at your medical school. It is not a letter of recommendation; it is a letter of evaluation describing your performance during medical school in comparison to your peers. At ERAS website you can download a guide for the preparation of the MSPE and handed it to your medical school if they are not familiar with the document. It must detail your academic history, awards, evaluations by your supervisors during basic and clinical curriculum, and any other special characteristic that may help you to get a position at a determined specialty. For IMG's it may be difficult to obtain such document since it is not a standard procedure in medical schools outside the United States. The MSPE is not an absolute requisite for your application, so if you can't obtain a full MSPE you can send a short LOR-like dean's letter or even no MSPE at all. Obviously, it will be a lot better to obtain a well structured MSPE, since it will give a few extra points to your application.