Chiles Rellenos con PicadilloPicadillo is a popular filling for chiles rellenos. It is made of minced pork, beef, or chicken, combined with onions, tomatoes, herbs, spices, and sometimes nuts, raisins, or other fruit. It's quite common in Mexico to serve two rellenos together, one filled with picadillo and another with cheese (see Stuffed Chiles with Cheese).