Handling the chuck as little as possible, divide it into fourths, shape each fourth into a ball, and with your thumb make a depression in the center or each ball. Fill each depression with a piece of the cheese and 1 teaspoon of the chiles and form the meat around the cheese mixture into a 1-inch patty. Season the hamburgers with salt and black pepper and grill them on oiled hot grill pan for 5 minutes on each side for medium-rare meat.
Make the guacamole while the hamburgers are grilling: Halve, pit, and peel the avocado, in a bowl mash the flesh coarse with a fork, and stir in the lemon juice, tomato, scallion, cumin, cilantro, and salt and pepper, to taste.
Transfer the hamburgers to the buns and top them with the guacamole.
Recipe courtesy of Gourmet Magazine