Place the cream cheese between 2 sheets of wax paper. Using a rolling pin, roll to form a rectangle about 6 inches by 8 inches and ½ inch thick. Remove the top sheet.
Cut the avocado in half, remove the pit, and scoop the flesh into a bowl. Mash until it is rather smooth, leaving some small chunks to add texture. Stir in the cilantro, onion, chile, lime juice, and salt.
Spread the avocado mixture evenly over the cream cheese.
Using the bottom sheet of paper, roll up the cream cheese to form a log.
Coat the roll completely with the sesame seeds. Cover lightly with plastic wrap and chill in the refrigerator for 15 minutes before serving. The roll can be made in advance and refrigerated for 6-8 hours, then set out at room temperature for 30 minutes before serving.
Unwrap the roll and place on a serving platter or tray. Serve with totopos or small crackers.