Use a medium-mesh sieve for straining the puree base. If a fine sieve were to be used instead, the soup would be watery because the tomato and tomatillo pulp would remain behind in the sieve. When cutting the pork butt, the size can vary. It does not have to be exactly 2 inches. But make sure the cuts are all about the same size so the pork meat can evenly cook in the oven.