Remove about 30 good size corn husks from the package and place in a large bowl of hot water. Soak for a couple of minutes, or until they are pliable, and drain. One by one, lay out a corn husk with the tapering end towards you. If the husks seem thin, layer a second corn husk on top. Leaving a 1 to 1 1/2-inch space at the bottom, a minimum of 1/2 inch space on the sides and a little more than that at the top, spread about 1/4 cup masa into an approximately 2x3-inch rectangle. The masa layer will be a little thicker than 1/4 inch. Place a very generous tablespoon of the Anaheim and onion filling along with a very generous tablespoon of the grated cheese lengthwise down the middle of the masa.
Pick up the two long sides of the corn husk and bring them together (you will see how the masa swaddles the filling) and fold the joined edges to one side, rolling them around the tamal. Fold up the empty tapering end, from the bottom up. This will form a closed bottom and the top will be left open. If the tamale won’t hold, you can tear strips from unused tamale wrappers and tie them around the bottom. Gently press from the bottom to the top to even the filling out, without squeezing too hard.
If not steaming right away, place on a plate or sheet pan, cover with plastic, and refrigerate. You can assemble them a day ahead of steaming. You can also steam them ahead and reheat (see below).
To prepare the tamalera or steamer: Place water in the bottom pan of a steamer, so that water is under the steamer basket or rack, and bring it to a simmer. If you want to be reassured that the water hasn’t all evaporated during the long steaming time, place a penny in it so you can hear it dancing around. Line the steamer with one or two layers of soaked corn husks.